Radionuclide transport in a single fissure

International Nuclear Information System (INIS)

Eriksen, T.E.

1983-01-01

Radionuclide migration have been studied in natural fissures orieted parallel to the axis of granite drill cores. A short pulse of the radionuclides solution was injected at one end of the fissure and the temporal change in radionuclide concentration of the eluate measured. After several hundred fissure volumes water had been pumped through the fissure following the radionuclide pulse the activity distribution on the fissure surfaces was measured. From the retardation of 152 Eu, 235 Np and 237 Pu it is concluded that these radionuclides are transported in the oxidation states Eu(III), Pu(IV) and Np(V). The distribution coefficients K sub (d) calculated from flow and activity distribution data on the basis of geometric surface area/volume ratios are of the same order as published K sub (d) values obtained from batch equilibrium experiments. (Author)

A study on the radionuclide transport by bacteria in geologic media

International Nuclear Information System (INIS)

Han, Byoung Sub

1997-02-01

The purpose of this paper is to provide a methodology to develop a predictive model based on a conceptual three phase system and to investigate the influence of bacteria and their generation on the transport of radionuclide in porous and fractured media. The mass balance for bacteria, substrate and radionuclide were formulated. To illustrate the model simply, an equilibrium condition was assumed to partition the substrate, bacteria and radionuclide concentrations between the solid soil matrix, aqueous phase, rock matrix and bacterial surface. From the numerical calculation of the radionuclide transport in the presence of bacteria, it was found that the growth of bacteria and supplied primary substrate as limiting or stimulating growth factor of bacteria are the most important factors of the radionuclide transport. We also found that, depend on the transport of bacteria the temporal and spatial distribution of radionuclide concentration was significantly altered. The model proposed in this study will improve the evaluation of the role of the bacteria in the transport of radionuclide in groundwater systems. Furthermore, this model would be usefully utilized in analyzing the important role of colloidal particulate on the overall performance of radioactive waste safety

Radionuclides: Accumulation and Transport in Plants.

Science.gov (United States)

Gupta, D K; Chatterjee, S; Datta, S; Voronina, A V; Walther, C

Application of radioactive elements or radionuclides for anthropogenic use is a widespread phenomenon nowadays. Radionuclides undergo radioactive decays releasing ionizing radiation like gamma ray(s) and/or alpha or beta particles that can displace electrons in the living matter (like in DNA) and disturb its function. Radionuclides are highly hazardous pollutants of considerable impact on the environment, food chain and human health. Cleaning up of the contaminated environment through plants is a promising technology where the rhizosphere may play an important role. Plants belonging to the families of Brassicaceae, Papilionaceae, Caryophyllaceae, Poaceae, and Asteraceae are most important in this respect and offer the largest potential for heavy metal phytoremediation. Plants like Lactuca sativa L., Silybum marianum Gaertn., Centaurea cyanus L., Carthamus tinctorius L., Helianthus annuus and H. tuberosus are also important plants for heavy metal phytoremediation. However, transfer factors (TF) of radionuclide from soil/water to plant ([Radionuclide]plant/[Radionuclide]soil) vary widely in different plants. Rhizosphere, rhizobacteria and varied metal transporters like NRAMP, ZIP families CDF, ATPases (HMAs) family like P1B-ATPases, are involved in the radio-phytoremediation processes. This review will discuss recent advancements and potential application of plants for radionuclide removal from the environment.

A study on the characteristics of colloid-associated radionuclide transport in porous media

International Nuclear Information System (INIS)

Jeong, Yun Chang

1997-02-01

Recently, the radionuclide transport in the form of colloids has been focused intensively in the safety assessment of a radioactive waste repository. As colloids are considered to be able to increase the transport rate of radionuclide through geologic media, the transport of radionuclide should be adjusted by the presence of colloids. The migration of dissolved radionuclide is expected to depend on various process such as advection, dispersion and interactions with soils, and, in addition, the transport of colloid-mediated radionuclide is considered to be more complicated because of the interactions between radionuclides and colloids. In this paper the migration behavior of colloid-associated radionuclides within subsurface are reviewed and studied in detail. The colloid-mediated transport system was modelled and simulated in order to illustrate the effects of colloids on the transport of radionuclide in the aquifer system. The transport rate of radionuclide is mainly controlled by a retardation factor which is controlled by colloidal behaviors, degree of adsorption, and the related geologic parameters. Therefore it is necessary to carefully understand the accelerating tendency of the retardation difference factor, and in this study the trends are analyzed, described and the retardation difference factor is mathematically defined, simplified and applied practically to the safety and performance assessment of a future repository

RADIONUCLIDE TRANSPORT MODELS UNDER AMBIENT CONDITIONS

Energy Technology Data Exchange (ETDEWEB)

S. Magnuson

2004-11-01

The purpose of this model report is to document the unsaturated zone (UZ) radionuclide transport model, which evaluates, by means of three-dimensional numerical models, the transport of radioactive solutes and colloids in the UZ, under ambient conditions, from the repository horizon to the water table at Yucca Mountain, Nevada.

EOS7R: Radionuclide transport for TOUGH2

International Nuclear Information System (INIS)

Oldenburg, C.M.; Pruess, K.

1995-11-01

EOS7R provides radionuclide transport capability for TOUGH2. EOS7R extends the EOS7 module (water, brine, and optional air) to model water, brine, parent component, daughter component, and optional air and heat. The radionuclide components follow a first-order decay law, and may adsorb onto the solid grains. Volatilization of the decaying components is modeled by Henry's Law. The decaying components are normally referred to as radionuclides, but they may in fact by any trace components that decay, adsorb, and volatilize. The decay process need not be radioactive decay, but could be any process that follows a first-order decay law, such as biodegradation. EOS7R includes molecular diffusion for all components in gaseous and aqueous phases using a simplified binary diffusion model. When EOS7R is used with standard TOUGH2, transport occurs by advection and molecular diffusion in all phases. When EOS7R is coupled with the dispersion module T2DM, one obtains T2DMR, the radionuclide transport version of T2DM. T2DMR models advection, diffusion, and hydrodynamic dispersion in rectangular two-dimensional regions. Modeling of radionuclide transport requires input parameters specifying the half-life for first-order decay, distribution coefficients for each rock type for adsorption, and inverse Henry's constants for volatilization. Options can be specified in the input file to model decay in inactive grid blocks and to read from standard EOS7 INCON files. The authors present a number of example problems to demonstrate application and accuracy of TOUGH2/EOS7R. One-dimensional simulation results agree well with analytical solutions. For a two-dimensional salt-dome flow problem, the final distribution of daughter radionuclide component is complicated by the presence of weak recirculation caused by density effects due to salinity

Development of TIGER code for radionuclide transport in a geochemically evolving region

International Nuclear Information System (INIS)

Mihara, Morihiro; Ooi, Takao

2004-01-01

In a transuranic (TRU) waste geological disposal facility, using cementitious materials is being considered. Cementitious materials will gradually dissolve in groundwater over the long-term. In the performance assessment report of a TRU waste repository in Japan already published, the most conservative radionuclide migration parameter set was selected considering the evolving cementitious material. Therefore, a tool to perform the calculation of radionuclide transport considering long-term geochemically evolving cementitious materials, named the TIGER code, Transport In Geochemically Evolving Region was developed to calculate a more realistic performance assessment. It can calculate radionuclide transport in engineered and natural barrier systems. In this report, mathematical equations of this code are described and validated with analytical solutions and results of other codes for radionuclide transport. The more realistic calculation of radionuclide transport for a TRU waste geological disposal system using the TIGER code could be performed. (author)

PATHWAY: a simulation model of radionuclide-transport through agricultural food chains

International Nuclear Information System (INIS)

Kirchner, T.B.; Whicker, F.W.; Otis, M.D.

1982-01-01

PATHWAY simulates the transport of radionuclides from fallout through an agricultural ecosystem. The agro-ecosystem is subdivided into several land management units, each of which is used either for grazing animals, for growing hay, or for growing food crops. The model simulates the transport of radionuclides by both discrete events and continuous, time-dependent processes. The discrete events include tillage of soil, harvest and storage of crops,and deposition of fallout. The continuous processes include the transport of radionuclides due to resuspension, weathering, rain splash, percolation, leaching, adsorption and desorption of radionuclides in the soil, root uptake, foliar absorption, growth and senescence of vegetation, and the ingestion assimilation, and excretion of radionuclides by animals. Preliminary validation studies indicate that the model dynamics and simulated values of radionuclide concentrations in several agricultural products agree well with measured values when the model is driven with site specific data on deposition from world-wide fallout

Development of a transportable system for radionuclide analysis

International Nuclear Information System (INIS)

Cunningham, W.C.; Anderson, D.L.; Lamont, W.H.; South, P.K.; Rury, M.A.; Beachley, G.M.; Ondov, J.M.

2008-01-01

Transportable radioanalytical systems were assembled and tested for quantitative determination of γ-emitting radionuclides and screening of β- emitting radionuclides. Standard operating procedures (SOPs), including instructions for assembly, disassembly, operation, sample collection and analysis, and all other procedures needed, were developed. Foods, as well as National Institute of Standards and Technology, International Atomic Energy Agency, and in-house Reference Materials were analyzed. An SOP for γ-emitting radionuclides was successfully tested at 3 locations. (author)

Radionuclide transport behavior in a generic geological radioactive waste repository.

Science.gov (United States)

Bianchi, Marco; Liu, Hui-Hai; Birkholzer, Jens T

2015-01-01

We performed numerical simulations of groundwater flow and radionuclide transport to study the influence of several factors, including the ambient hydraulic gradient, groundwater pressure anomalies, and the properties of the excavation damaged zone (EDZ), on the prevailing transport mechanism (i.e., advection or molecular diffusion) in a generic nuclear waste repository within a clay-rich geological formation. By comparing simulation results, we show that the EDZ plays a major role as a preferential flowpath for radionuclide transport. When the EDZ is not taken into account, transport is dominated by molecular diffusion in almost the totality of the simulated domain, and transport velocity is about 40% slower. Modeling results also show that a reduction in hydraulic gradient leads to a greater predominance of diffusive transport, slowing down radionuclide transport by about 30% with respect to a scenario assuming a unit gradient. In addition, inward flow caused by negative pressure anomalies in the clay-rich formation further reduces transport velocity, enhancing the ability of the geological barrier to contain the radioactive waste. On the other hand, local high gradients associated with positive pressure anomalies can speed up radionuclide transport with respect to steady-state flow systems having the same regional hydraulic gradients. Transport behavior was also found to be sensitive to both geometrical and hydrogeological parameters of the EDZ. Results from this work can provide useful knowledge toward correctly assessing the post-closure safety of a geological disposal system. © 2014, National Ground Water Association.

The effect of bacterial generation on the transport of radionuclide in porous media

International Nuclear Information System (INIS)

Han, B.S.; Lee, K.J.

1997-01-01

The purpose of this paper is to provide a methodology to develop a predictive model based on a conceptual three-phase system and to investigate the influence of bacteria and their generation on the radionuclide transport in porous media. The mass balance equations for bacteria, substrate and radionuclide were formulated. To illustrate the model simply, an equilibrium condition was assumed to partition the substrate, bacteria and radionuclide concentrations, between the solid soil matrix, aqueous phase and bacterial surface. From the numerical calculation of radionuclide transport in the presence of bacteria, it was found that the growth of bacterial and supplied primary substrate as a limiting or stimulating growth factor of bacteria are the most important factors of the radionuclide transport. It was also found that, depending on the transport of bacteria, the temporal and spatial distribution of the radionuclide concentration was significantly affected. The model proposed in this study will improve the evaluation of the role of the bacteria to the transport of radionuclide in groundwater systems. Furthermore, this model can be usefully utilized in analyzing the important role of colloidal particulate on the overall performance of radioactive waste safety. (Author)

The vertical distribution of radionuclides in a Ribble Estuary saltmarsh: transport and deposition of radionuclides

International Nuclear Information System (INIS)

Brown, J.E.; McDonald, P.; Parker, A.; Rae, J.E.

1999-01-01

Routine discharges of low-level liquid radioactive waste by British Nuclear Fuels plc (BNFL) at Sellafield and Springfields have resulted in enhanced levels of radionuclides in sediments of the Ribble Estuary, NW England, UK. Variations in radionuclide concentrations ( 137 Cs, 230 Th, and 239240 Pu) with depth in a mature saltmarsh core were analysed in order to investigate historical discharge trends and waste-dispersal mechanisms. Core samples from Longton/Hutton Marsh were analysed by gamma-spectrometry and α-spectrometry for radionuclides and by laser granulometry to establish grain-size variations with depth. Distinct subsurface maxima were present for 137 Cs and 239240 Pu with activities as high as 4500 Bq kg -1 for 137 Cs and 600 Bq kg -1 for 239240 Pu. Thorium-230 exhibited complex activity profiles with depth, specific activities ranging between 200 and 2400 Bq kg -1 . The vertical distributions of Sellafield-derived radionuclides ( 137 Cs and 239240 Pu) in mature saltmarsh deposits reflect the time-integrated discharge pattern from Sellafield, implying a transport mechanism that has involved the mixing of sediment labelled with radioactivity from recent discharges and sediment labelled from historical discharge events before deposition. A mechanism involving the transport of contaminated silt therefore seems to dominate. The vertical distribution of Springfields-derived 230 Th in the same areas reflects the annual gross-α discharge pattern from BNFL Springfields. In contrast to the Sellafield-derived radionuclides, a fairly rapid transport mechanism from source to sink is implied, with little or no time for mixing with radionuclides discharged years earlier. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

SCATTER: Source and Transport of Emplaced Radionuclides: Code documentation

International Nuclear Information System (INIS)

Longsine, D.E.

1987-03-01

SCATTER simulated several processes leading to the release of radionuclides to the site subsystem and then simulates transport via the groundwater of the released radionuclides to the biosphere. The processes accounted for to quantify release rates to a ground-water migration path include radioactive decay and production, leaching, solubilities, and the mixing of particles with incoming uncontaminated fluid. Several decay chains of arbitrary length can be considered simultaneously. The release rates then serve as source rates to a numerical technique which solves convective-dispersive transport for each decay chain. The decay chains are allowed to have branches and each member can have a different radioactive factor. Results are cast as radionuclide discharge rates to the accessible environment

A model for radionuclide transport in the Cooling Water System

International Nuclear Information System (INIS)

Kahook, S.D.

1992-08-01

A radionuclide transport model developed to assess radiological levels in the K-reactor Cooling Water System (CWS) in the event of an inadvertent process water (PW) leakage to the cooling water (CW) in the heat exchangers (HX) is described. During and following a process water leak, the radionuclide transport model determines the time-dependent release rates of radionuclide from the cooling water system to the environment via evaporation to the atmosphere and blow-down to the Savannah River. The developed model allows for delay times associated with the transport of the cooling water radioactivity through cooling water system components. Additionally, this model simulates the time-dependent behavior of radionuclides levels in various CWS components. The developed model is incorporated into the K-reactor Cooling Tower Activity (KCTA) code. KCTA allows the accident (heat exchanger leak rate) and the cooling tower blow-down and evaporation rates to be described as time-dependent functions. Thus, the postulated leak and the consequence of the assumed leak can be modelled realistically. This model is the first of three models to be ultimately assembled to form a comprehensive Liquid Pathway Activity System (LPAS). LPAS will offer integrated formation, transport, deposition, and release estimates for radionuclides formed in a SRS facility. Process water and river water modules are forthcoming as input and downstream components, respectively, for KCTA

CASCADER: An M-chain gas-phase radionuclide transport and fate model

International Nuclear Information System (INIS)

Lindstrom, F.T.; Cawlfield, D.E.; Emer, D.F.; Shott, G.J.; Donahue, M.E.

1993-02-01

Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and diffusion. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. CASCADER is a gas-phase, one-space dimensional transport and fate model for M-chain radionuclides in very dry homogeneous or heterogeneous soil. This model contains barometric pressure-induced advection and diffusion together with linear irreversible and linear reversible sorption for each radionuclide. The advection velocity is derived from an embedded air-pumping submodel. The air-pumping submodel is based on an assumption of isothermal conditions, which is driven by barometric pressure. CASCADER allows the concentration of source radionuclides to decay via the classical Bateman chain of simple, first-order kinetic processes. The transported radionuclides also decay via first-order processes while in the soil. A mass conserving, flux-type inlet and exit set of boundary conditions are used. The user must supply the initial distribution for the parent radionuclide in the soil. The initial daughter distribution is found using equilibrium rules. The model is user friendly as it uses a prompt-driven, free-form input. The code is ANSI standard Fortran 77

CASCADER: An m-chain gas-phase radionuclide transport and fate model

International Nuclear Information System (INIS)

Lindstrom, F.T.; Cawlfield, D.E.; Emer, D.F.; Shott, G.J.; Donahue, M.E.

1992-06-01

Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes as they are advected and/or dispersed. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. CASCADER is a gas-phase, one space dimensional transport and fate model for an m-chain of radionuclides in very dry soil. This model contains barometric pressure-induced advection and diffusion together with linear irreversible and linear reversible sorption for each radionuclide. The advocation velocity is derived from an embedded air-pumping submodel. The airpumping submodel is based on an assumption of isothermal conditions and is barometric pressure driven. CASCADER allows the concentration of source radionuclides to decay via the classical Bateman chain of simple, first-order kinetic processes. The transported radionuclides also decay via first-order processes while in the soil. A mass conserving, flux-type inlet and exit set of boundary conditions is used. The user must supply the initial distribution for the parent radionuclide in the soil. The initial daughter distribution is found using equilibrium rules. The model is user friendly as it uses a prompt-driven, free-form input. The code is ANSI standard Fortran 77

Hydrologic transport of radionuclides from low-level waste burial grounds

International Nuclear Information System (INIS)

Duguid, J.O.

1979-01-01

The physical characteristics of the virgin site and of the disturbed site after burial drastically affect the transport of radionuclides from buried waste. The disturbance of the land surface during the waste burial operation causes changes in the local ground-water regimen. These changes can increase the water table elevation and cause the occurrence of perched water in burial trenches. The combination of these changes may lead to submersion of the waste and to increased radionuclide transport from the burial site in both surface and groundwater. Factors such as ion exchange can retard or in some cases, with competing ions, can also mobilize radionuclides and increase their discharge into ground and surface water. Because of complexing agents (organics) contained in the waste, increased mobility of some radionuclides can be expected. The chemical form of radionuclides in the water, the ground-water quality, and the chemistry of the geologic formation in which the waste is buried all influence the movement of radionuclides in the hydrologic system. For the assessment of the environmental impact of low-level waste burial, models capable of simulating both the chemical and the physical factors that affect hydrologic transport must be available. Several models for conducting such simulation are presently available. However, the input parameters used in these models are highly variable; and the accuracy of parameter measurement must be considered in evaluating the reliability of simulated results

A meshless approach to radionuclide transport calculations

International Nuclear Information System (INIS)

Perko, J.; Sarler, B.

2005-01-01

Over the past thirty years numerical modelling has emerged as an interdisciplinary scientific discipline which has a significant impact in engineering and design. In the field of numerical modelling of transport phenomena in porous media, many commercial codes exist, based on different numerical methods. Some of them are widely used for performance assessment and safety analysis of radioactive waste repositories and groundwater modelling. Although they proved to be an accurate and reliable tool, they have certain limitations and drawbacks. Realistic problems often involve complex geometry which is difficult and time consuming to discretize. In recent years, meshless methods have attracted much attention due to their flexibility in solving engineering and scientific problems. In meshless methods the cumbersome polygonization of calculation domain is not necessary. By this the discretization time is reduced. In addition, the simulation is not as discretization density dependent as in traditional methods because of the lack of polygon interfaces. In this work fully meshless Diffuse Approximate Method (DAM) is used for calculation of radionuclide transport. Two cases are considered; First 1D comparison of 226 Ra transport and decay solved by the commercial Finite Volume Method (FVM) and Finite Element Method (FEM) based packages and DAM. This case shows the level of discretization density dependence. And second realistic 2D case of near-field modelling of radionuclide transport from the radioactive waste repository. Comparison is made again between FVM based code and DAM simulation for two radionuclides: Long-lived 14 C and short-lived 3 H. Comparisons indicate great capability of meshless methods to simulate complex transport problems and show that they should be seriously considered in future commercial simulation tools. (author)

Radionuclide Transport Models Under Ambient Conditions

International Nuclear Information System (INIS)

Moridis, G.; Hu, Q.

2000-01-01

The purpose of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada. This is in accordance with the ''AMR Development Plan U0060, Radionuclide Transport Models Under Ambient Conditions'' (CRWMS M and O 1999a). This AMR supports the UZ Flow and Transport Process Model Report (PMR). This AMR documents the UZ Radionuclide Transport Model (RTM). This model considers: the transport of radionuclides through fractured tuffs; the effects of changes in the intensity and configuration of fracturing from hydrogeologic unit to unit; colloid transport; physical and retardation processes and the effects of perched water. In this AMR they document the capabilities of the UZ RTM, which can describe flow (saturated and/or unsaturated) and transport, and accounts for (a) advection, (b) molecular diffusion, (c) hydrodynamic dispersion (with full 3-D tensorial representation), (d) kinetic or equilibrium physical and/or chemical sorption (linear, Langmuir, Freundlich or combined), (e) first-order linear chemical reaction, (f) radioactive decay and tracking of daughters, (g) colloid filtration (equilibrium, kinetic or combined), and (h) colloid-assisted solute transport. Simulations of transport of radioactive solutes and colloids (incorporating the processes described above) from the repository horizon to the water table are performed to support model development and support studies for Performance Assessment (PA). The input files for these simulations include transport parameters obtained from other AMRs (i.e., CRWMS M and O 1999d, e, f, g, h; 2000a, b, c, d). When not available, the parameter values used are obtained from the literature. The results of the simulations are used to evaluate the transport of radioactive solutes and colloids, and

Radionuclide transport as vapor through unsaturated fractured rock

International Nuclear Information System (INIS)

Green, R.T.

1986-01-01

The objective of this study is to identify and examine potential mechanisms of radionuclide transport as vapor at a high-level radioactive waste repository located in unsaturated fractured rock. Transport mechanisms and processes have been investigated near the repository and at larger distances. Transport mechanisms potentially important at larger distances include ordinary diffusion, viscous flow and free convection. Ordinary diffusion includes self and binary diffusion, Knudsen flow and surface diffusion. Pressure flow and slip flow comprise viscous flow. Free convective flow results from a gas density contrast. Transport mechanisms or processes dominant near the repository include ordinary diffusion, viscous flow plus several mechanisms whose driving forces arise from the non-isothermal, radioactive nature of high-level waste. The additional mechanisms include forced diffusion, aerosol transport, thermal diffusion and thermophoresis. Near a repository vapor transport mechanisms and processes can provide a significant means of transport from a failed canister to the geologic medium from which other processes can transport radionuclides to the accessible environment. These issues are believed to be important factors that must be addressed in the assessment of specific engineering designs and site selection of any proposed HLW repository

Hydrologic transport of radionuclides from low-level waste burial grounds

International Nuclear Information System (INIS)

Duguid, J.O.

1977-01-01

The physical characteristics of the virgin site and of the disturbed site after burial drastically affect the transport of radionuclides from buried waste. The disturbance of the land surface during the waste burial operation causes changes in the local ground-water regimen. These changes can increase the water table elevation and cause the occurrence of perched water in burial trenches. The combination of these changes may lead to submersion of the waste and to increased radionuclide transport from the burial site in both surface and ground water. Factors such as ion exchange can retard or in some cases, with competing ions, can also mobilize radionuclides and increase their discharge into ground and surface water. Because of complexing agents (organics) contained in the waste, increased mobility of some radionuclides can be expected. The chemical form of radionuclides in the water, the ground-water quality, and the chemistry of the geologic formation in which the waste is buried all influence the movement of radionuclides in the hydrologic system. For the assessment of the environmental impact of low-level waste burial, models capable of simulating both the chemical and the physical factors that affect hydrologic transport must be available. Several models for conducting such simulation are presently available. However,the input parameters used in these models are highly variable, and the accuracy of parameter measurement must be considered in evaluating the reliability of simulated results

Speciation and transport of radionuclides in ground water

International Nuclear Information System (INIS)

Robertson, D.E.; Toste, A.P.; Abel, K.H.; Cowan, C.E.; Jenne, E.A.; Thomas, C.W.

1984-01-01

Studies of the chemical speciation of a number of radionuclides migrating in a slightly contaminated ground water plume are identifying the most mobile species and providing an opportunity to test and/or validate geochemical models of radionuclide transport in ground waters. Results to date have shown that most of the migrating radionuclides are present in anionic or nonionic forms. These include anionic forms of 55 Fe, 60 Co, /sup 99m/Tc, 106 Ru, 131 I, and nonionic forms of 63 Ni and 125 Sb. Strontium-70 and a small fraction of the mobile 60 Co are the only cationic radionuclides which have been detected moving in the ground water plume beyond 30 meters from the source. A comparison of the observed chemical forms with the predicted species calculated from modeling thermodynamic data and ground water chemical parameters has indicated a good agreement for most of the radioelements in the system, including Tc, Np, Cs, Sr, Ce, Ru, Sb, Zn, and Mn. The discrepancies between observed and calculated solutions species were noted for Fe, Co, Ni and I. Traces of Fe, Co, and Ni were observed to migrate in anionic or nonionic forms which the calculations failed to predict. These anionic/nonionic species may be organic complexes having enhanced mobility in ground waters. The radioiodine, for example, was shown to behave totally as an anion but further investigation revealed that 49-57% of this anionic iodine was organically bound. The ground water and aqueous extracts of trench sediments contain a wide variety of organic compounds, some of which could serve as complexing agents for the radionuclides. These results indicate the need for further research at a variety of field sites in defining precisely the chemical forms of the mobile radionuclide species, and in better understanding the role of dissolved organic materials in ground water transport of radionuclides

Colloid-Facilitated Transport of Radionuclides Through The Vadose Zone

International Nuclear Information System (INIS)

Markus Flury; James B. Harsh; John F. McCarthy' Peter C. Lichtner; John M. Zachara

2007-01-01

The main purpose of this project was to advance the basic scientific understanding of colloid and colloid-facilitated Cs transport of radionuclides in the vadose zone. We focused our research on the hydrological and geochemical conditions beneath the leaking waste tanks at the USDOE Hanford reservation. Specific objectives were (1) to determine the lability and thermodynamic stability of colloidal materials, which form after reacting Hanford sediments with simulated Hanford Tank Waste, (2) to characterize the interactions between colloidal particles and contaminants, i.e., Cs and Eu, (3) to determine the potential of Hanford sediments for in situ mobilization of colloids, (4) to evaluate colloid-facilitated radionuclide transport through sediments under unsaturated flow, (5) to implement colloid-facilitated contaminant transport mechanisms into a transport model, and (6) to improve conceptual characterization of colloid-contaminant-soil interactions and colloid-facilitated transport for clean-up procedures and long-term risk assessment

Transport and accumulation of radionuclides in soil

International Nuclear Information System (INIS)

Frissel, M.J.; Jakubick, A.T.; Kernforschungszentrum Karlsruhe G.m.b.H.

1979-01-01

The movement of radioactive isotopes through the water phase of soils is by far the most important. Most of the water-transported radioactive isotopes (radionuclides) occur via their dissolved salts, while the rest is carried by small soil particles to which the radionuclides are adsorbed. In the case of many chemicals, it is possible to calculate the movement or migration through soil from adsorption measurements made in the laboratory and from knowledge of the flow pattern of soil water. With increasing complexity of the chemical-soil-water system predictions become more uncertain. In the case of radionuclides the amounts expressed in units of weight are extremely small. This renders terms such as 'soluble' or 'insoluble' inapplicable. In these cases transport of 'radiocolloids' and adsorbed particles as 'insoluble' compounds may be more significant. For fallout strontium and cesium reliable predictive models have been developed. For fallout plutonium such models are under development. For calculations or predictions of the migration of radioactive material from deep soil layers to the soil surface fewer mathematical models are available. Many laboratory studies cannot yet be made due to lack of suitable soil samples from the sites under study. Nevertheless safety studies already carried out in a preliminary way are reliable, since factos such as adsorption of radionuclides on soils are neglected; consequently most safety studies overestimate possible risks. Further studies are required to ascertain how 'pessimistic' are the present safety criteriy. (orig./MG) [de

Simulation of radionuclide transport in U.S. agriculture

International Nuclear Information System (INIS)

Sharp, R.D.; Baes, C.F. III.

1982-01-01

Because of the recent concern about the impact of energy technologies on man and related health effects, there has emerged a need for models to calculate or predict the effects of radionuclides on man. A general overview is presented of a model that calculates the ingrowth of radionuclides into man's food chain. The FORTRAN IV computer program TERRA, Transport of Environmentally Released Radionuclides in Agriculture, simulates the build-up of radionuclides in soil, four plant food compartments, in meat and milk from beef, and in the livestock food compartments that cause radionuclide build-up in milk and meat from beef. A large data set of spatially oriented parameters has been developed in conjunction with TERRA. This direct-access data set is called SITE, Specific Information on the Terrestrial Environment, and contains 35 parameters for each of 3525 half-degree longitude-latitude cells which define the lower 48 states. TERRA and SITE are used together as a package for determining radionuclide concentrations in man's food anywhere within the conterminous 48 states due to atmospheric releases

RADIONUCLIDE DISPERSION RATES BY AEOLIAN, FLUVIAL, AND POROUS MEDIA TRANSPORT

International Nuclear Information System (INIS)

Walton, J.; Goodell, P.; Brashears, C.; French, D.; Kelts, A.

2005-01-01

Radionuclide transport was measured from high grade uranium ore boulders near the Nopal I Site, Chihuahua, Mexico. High grade uranium ore boulders were left behind after removal of a uranium ore stockpile at the Prior High Grade Stockpile (PHGS). During the 25 years when the boulder was present, radionuclides were released and transported by sheetflow during precipitation events, wind blown resuspension, and infiltration into the unsaturated zone. In this study, one of the boulders was removed, followed by grid sampling of the surrounding area. Measured gamma radiation levels in three dimensions were used to derive separate dispersion rates by the three transport mechanisms

RADIONUCLIDE DISPERSION RATES BY AEOLIAN, FLUVIAL, AND POROUS MEDIA TRANSPORT

Energy Technology Data Exchange (ETDEWEB)

J. Walton; P. Goodell; C. Brashears; D. French; A. Kelts

2005-07-11

Radionuclide transport was measured from high grade uranium ore boulders near the Nopal I Site, Chihuahua, Mexico. High grade uranium ore boulders were left behind after removal of a uranium ore stockpile at the Prior High Grade Stockpile (PHGS). During the 25 years when the boulder was present, radionuclides were released and transported by sheetflow during precipitation events, wind blown resuspension, and infiltration into the unsaturated zone. In this study, one of the boulders was removed, followed by grid sampling of the surrounding area. Measured gamma radiation levels in three dimensions were used to derive separate dispersion rates by the three transport mechanisms.

Radionuclide transport and retardation in tuff

International Nuclear Information System (INIS)

Vine, E.N.; Bayhurst, B.P.; Daniels, W.R.; DeVilliers, S.J.; Erdal, B.R.; Lawrence, F.O.; Wolfsberg, K.

1980-01-01

Batch measurements provide an understanding of which experimental variables are important. For example, sorption ratios vary little with particle size (and surface area); however, groundwater composition and rock composition are quite important. A general correlation has been identified between mineralogy (major phases) and degree of sorption for strontium, cesium, and barium. Although these are approximate, a more detailed analysis may be possible as more samples are studied and the data base increased. Data from crushed tuff columns indicate that, except in simple cases where sorption coefficients are relatively low, and ion-exchange equilibria not only exist but are the dominant mechanism for removal of radioisotopes from solution, the simple relation between the sorption ratio R/sub d/ (or K/sub d/) and the relative velocity of radionuclides with respect to groundwater velocity may be insufficient to permit accurate modeling of the retardation of radionuclides. Additional work on whole core columns and larger blocks of intact material is required to better understand radionuclide sorption and transport through rock

Transport of radionuclides in the atmosphere during complex meteorological conditions

International Nuclear Information System (INIS)

Antic, D.; Telenta, B.

1991-01-01

Radionuclides from various sources (nuclear and fossil fuel power plants, nuclear facilities, medical facilities, etc.) are being released to the atmosphere. The meteorological conditions determine the atmospheric turbulence, dispersion, and removal processes of the radionuclides. A two-dimensional version of the cloud model based on the Klemp-Wilhelmson dynamic and Lin et al.'s microphysics and thermodynamics has been adapted and used to simulate the transport of radionuclides emitted from a power plant or other source to the atmosphere. Calculations of the trajectories and radii for a few puffs are included in this paper. These numerical investigations show that the presented model can be used for the transport simulation of radionuclides and for the assessment of the radiological impact of power plants and other sources in safety assessments and comparative studies. Because it can simulate puff trajectories, this model is especially valuable in the presence of complex meteorological conditions

The separation of radionuclide migration by solution and particle transport in LLRW repository buffer material

International Nuclear Information System (INIS)

Torok, J.; Buckley, L.P.; Woods, B.L.

1989-01-01

Laboratory-scale lysimeter experiments were performed with simulated waste forms placed in candidate buffer materials which have been chosen for a low-level radioactive waste repository. Radionuclide releases into the effluent water and radionuclide capture by the buffer material were determined. The results could not be explained by traditional solution transport mechanisms, and transport by particles released from the waste form and/or transport by buffer particles were suspected as the dominant mechanism for radionuclide release from the lysimeters. To elucidate the relative contribution of particle and solution transport, the waste forms were replaced by a wafer of neutron-activated buffer soaked with selected soluble isotopes. Particle transport was determined by the movement of gamma-emitting neutron-activation products through the lysimeter. Solution transport was quantified by comparing the migration of soluble radionuclides relative to the transport of neutron activation products. The new approach for monitoring radionuclide migration in soil is presented. It facilitates the determination of most of the fundamental coefficients required to model the transport process

Chemical controls on subsurface radionuclide transport

International Nuclear Information System (INIS)

King, K.J.; Killey, R.W.D.

1990-01-01

Chemical and biochemical processes can affect the movement of contaminants in groundwater. Materials can be almost completely removed from circulation by processes such as precipitation and coprecipitation. Organic compounds or contaminants that are hazardous may be degraded or formed during groundwater transport. Studies at the Chalk River Laboratories of AECL have focused on radionuclide transport, although other contaminants have been and are being investigated. This paper summarizes findings from research that extends back more than 30 years. Much of the work on reactive contaminant transport has centered on 90 Sr; other contaminants have also been considered, however, and features of their behaviour are also reviewed. (25 refs., 5 figs., 4 tabs.)

Bioturbation as a mechanism for radionuclide transport in soil: relevance of earthworms

International Nuclear Information System (INIS)

Mueller-Lemans, H.; Dorp, F. van

1996-01-01

In the context of safety analyses performed for radioactive waste repositories, one important group of scenarios assumes that radionuclides escaping from a repository will reach the biosphere via groundwater. Consequently, when calculating radionuclide migration in the biosphere, most of the models used to date concentrate on transport in the liquid phase. In the soil, however, transport in the solid phase can also be important, particularly when burrowing animals displace the soil together with sorbed and low-solubility radionuclides. Given the conditions prevailing in agricultural areas of central Europe, it is mainly earthworms which play a significant role in material displacement and these will be the subject of this report. A numerical example is used to present the equations which, for given distribution coefficients, can be applied to calculate the portions of the transfer coefficient which can be attributed to transport in the liquid and solid phases. The results demonstrate that material transport by soil fauna, and particularly by earthworms, is a relevant mechanism in many cases, especially for the upward transport of strongly sorbing radionuclides. It should therefore be considered in biosphere models. (Author)

Influence of fracture networks on radionuclide transport from solidified waste forms

Energy Technology Data Exchange (ETDEWEB)

Seetharam, S.C., E-mail: suresh.seetharam@sckcen.be [Performance Assessments Unit, Institute for Environment, Health and Safety, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, B-2400 Mol (Belgium); Perko, J.; Jacques, D. [Performance Assessments Unit, Institute for Environment, Health and Safety, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, B-2400 Mol (Belgium); Mallants, D. [CSIRO Land and Water, Waite Road – Gate 4, Glen Osmond, SA 5064 (Australia)

2014-04-01

Highlights: • Magnitude of peak radionuclide fluxes is less sensitive to the fracture network geometry. • Time of peak radionuclide fluxes is sensitive to the fracture networks. • Uniform flow model mimics a limiting case of a porous medium with large number of fine fractures. • Effect of fracture width on radionuclide flux depends on the ratio of fracture to matrix conductivity. • Effect of increased dispersivity in fractured media does not always result in a lower peak flux for specific fracture networks due to higher concentrations adjacent to the fracture plane. - Abstract: Analysis of the effect of fractures in porous media on fluid flow and mass transport is of great interest in many fields including geotechnical, petroleum, hydrogeology and waste management. This paper presents sensitivity analyses examining the effect of various hypothetical fracture networks on the performance of a planned near surface disposal facility in terms of radionuclide transport behaviour. As it is impossible to predict the initiation and evolution of fracture networks and their characteristics in concrete structures over time scales of interest, several fracture networks have been postulated to test the sensitivity of radionuclide release from a disposal facility. Fluid flow through concrete matrix and fracture networks are modelled via Darcy's law. A single species radionuclide transport equation is employed for both matrix and fracture networks, which include the processes advection, diffusion, dispersion, sorption/desorption and radioactive decay. The sensitivity study evaluates variations in fracture network configuration and fracture width together with different sorption/desorption characteristics of radionuclides in a cement matrix, radioactive decay constants and matrix dispersivity. The effect of the fractures is illustrated via radionuclide breakthrough curves, magnitude and time of peak mass flux, cumulative mass flux and concentration profiles. For the

Influence of fracture networks on radionuclide transport from solidified waste forms

International Nuclear Information System (INIS)

Seetharam, S.C.; Perko, J.; Jacques, D.; Mallants, D.

2014-01-01

Highlights: • Magnitude of peak radionuclide fluxes is less sensitive to the fracture network geometry. • Time of peak radionuclide fluxes is sensitive to the fracture networks. • Uniform flow model mimics a limiting case of a porous medium with large number of fine fractures. • Effect of fracture width on radionuclide flux depends on the ratio of fracture to matrix conductivity. • Effect of increased dispersivity in fractured media does not always result in a lower peak flux for specific fracture networks due to higher concentrations adjacent to the fracture plane. - Abstract: Analysis of the effect of fractures in porous media on fluid flow and mass transport is of great interest in many fields including geotechnical, petroleum, hydrogeology and waste management. This paper presents sensitivity analyses examining the effect of various hypothetical fracture networks on the performance of a planned near surface disposal facility in terms of radionuclide transport behaviour. As it is impossible to predict the initiation and evolution of fracture networks and their characteristics in concrete structures over time scales of interest, several fracture networks have been postulated to test the sensitivity of radionuclide release from a disposal facility. Fluid flow through concrete matrix and fracture networks are modelled via Darcy's law. A single species radionuclide transport equation is employed for both matrix and fracture networks, which include the processes advection, diffusion, dispersion, sorption/desorption and radioactive decay. The sensitivity study evaluates variations in fracture network configuration and fracture width together with different sorption/desorption characteristics of radionuclides in a cement matrix, radioactive decay constants and matrix dispersivity. The effect of the fractures is illustrated via radionuclide breakthrough curves, magnitude and time of peak mass flux, cumulative mass flux and concentration profiles. For the

Transient simulation and sensitivity analysis for transport of radionuclides in a saturated-unsaturated groundwater flow system

International Nuclear Information System (INIS)

Chen, H.H.

1980-01-01

Radionuclide transport by groundwater flow is an important pathway in the assessment of the environmental impact of radioactive waste disposal to the biosphere. A numerical model was developed to simulate radionuclide transport by groundwater flow and predict the radionuclide discharge rate to the biosphere. A sensitivity analysis methodology was developed to address the sensitivity of the input parameters of the radionuclide transport equation to the specified response of interest

MIGFRAC - a code for modelling of radionuclide transport in fracture media

International Nuclear Information System (INIS)

Satyanarayana, S.V.M.; Mohankumar, N.; Sasidhar, P.

2002-05-01

Radionuclides migrate through diffusion process from radioactive waste disposal facilities into fractures present in the host rock. The transport phenomenon is aided by the circulating ground waters. To model the transport of radionuclides in the charnockite rock formations present at Kalpakkam, a numerical code - MIGFRAC has been developed at SHINE Group, IGCAR. The code has been subjected to rigorous tests and the results of the build up of radionuclide concentrations are validated with a test case up to a distance of 100 meter along the fracture. The report discusses the model, code features and the results obtained up to a distance of 400 meter are presented. (author)

ITE CHARACTERIZATION TO SUPPORT CONCEPTUAL MODEL DEVELOPMENT FOR SUBSURFACE RADIONUCLIDE TRANSPORT

Science.gov (United States)

Remediation of radionuclide contaminants in ground water often begins with the development of conceptual and analytical models that guide our understanding of the processes controlling radionuclide transport. The reliability of these models is often predicated on the collection o...

Sediment-associated transport and redistribution of Chernobyl fallout radionuclides

International Nuclear Information System (INIS)

Walling, D.E.; Rowan, J.S.; Bradley, S.B.

1989-01-01

Fallout of Chernobyl-derived radionuclides over the United Kingdom evidenced marked spatial variation. Relatively high levels were recorded in central Wales, but they declined rapidly to the east. As a result the headwaters of the River Severn received significant inputs of fallout, whereas only low levels were recorded over the middle and lower reaches. Measurements of the caesium-137 content of suspended sediment transported by the River Severn and of channel and floodplain sediments collected from various locations within the basin have been used to assess the importance of fluvial transport and redistribution of Chernobyl-derived radionuclides. High concentrations of caesium-137 (up to 1450 mBqg -1 ) were recorded in suspended sediment collected from the lower reaches of the river shortly after the Chernobyl incident and substantial accumulations of Chernobyl-derived radionuclides have been detected in floodplain and channel sediments collected from areas which received only low levels of fallout directly. (author)

Transport of radionuclides by concentrated brine in a porous medium with micropore-macropore structure

International Nuclear Information System (INIS)

Hassanizadeh, S.M.

1987-01-01

This work concerns itself with the study of effects of soil aggregation and high salt concentrations on the transport of radionuclides by concentrated brine flowing through an aggregated porous medium. The medium is considered to be composed of porous rock aggregates separated by macropores through which the brine flows and transport of salt and radionuclides takes place. The aggregates contain dead-end pores, cracks, and stationary pockets collectively called micropores. The micropore space does not contribute to the flow, but it serves as a storage for salt and radionuclides. Adsorption of radionuclides takes place at internal surfaces of aggregates where they assume that a linear equilibrium isotherm describes the process. A one-dimensional numerical model is developed which is based on two sets of equations: one set for the flow and transport of salt and another set for transport of radionuclides. Results of numerical experiments clearly indicate that the existence of high salt concentrations markedly reduces the peak of nuclides concentration and slows down their movement. Also, it is found that diffusive mass exchange between macropores and aggregates results in a pronounced lowering of the radionuclides concentration peaks. 9 references, 7 figures

Analysis of radionuclide transport through fissured porous media with a perturbation method

Energy Technology Data Exchange (ETDEWEB)

Banat, M [JGC Corp., Tokyo (Japan)

1995-04-01

This paper presents a specific procedure for obtaining solutions for the transport of radionuclides in a fissured porous media. The concentration profiles are deduced for a wide range of Peclet numbers using a perturbation method with a multiscale of time. Results show clearly that because of an increase of longitudinal dispersion, the radionuclide moves faster with respect to the case of zero dispersion (i.e. an infinite Peclet number). The main purpose of this paper is to demonstrate the practical advantage of the present calculation method with respect to the classical numerical and analytical methods used for radionuclide transport. (author).

Field studies of radionuclide transport at the Chalk River Laboratories

International Nuclear Information System (INIS)

Champ, D.R.; Killey, R.W.D.; Moltyaner, G.L.

1991-01-01

In this paper the authors summarize the results of: in situ field column experiments to study the transport behaviour of several long-lived radionuclides, 4 natural gradient non-reactive radiotracer injection experiments at the Chalk River Laboratories (CRL) Twin Lake Tracer Test Site, and a model validation study that used data for 90 Sr from two well-defined contaminated groundwater flow systems at CRL. The paper also describes a current re-evaluation of radionuclide release and transport from a 1960 experimental burial (in a CRL sand aquifer) of glass blocks containing fission and activation products. (J.P.N.)

The RADionuclide Transport, Removal, and Dose (RADTRAD) code

International Nuclear Information System (INIS)

Miller, L.A.; Chanin, D.I.; Lee, J.

1993-01-01

The RADionuclide Transport, Removal, And Dose (RADTRAD) code is designed for US Nuclear Regulatory Commission (USNRC) use to calculate the radiological consequences to the offsite population and to control room operators following a design-basis accident at Light Water Reactor (LWR) power plants. This code utilizes updated reactor accident source terms published in draft NUREG-1465, ''Accident Source Terms for Light-Water Nuclear Power Plants.'' The code will track the transport of radionuclides as they are released from the reactor pressure vessel, travel through the primary containment and other buildings, and are released to the environment. As the radioactive material is transported through the primary containment and other buildings, credit for several removal mechanisms may be taken including sprays, suppression pools, overlying pools, filters, and natural deposition. Simple models are available for these different removal mechanisms that use, as input, information about the conditions in the plant and predict either a removal coefficient (λ) or decontamination factor. The user may elect to use these models or input a single value for a removal coefficient or decontamination factor

Mathematical Basis and Test Cases for Colloid-Facilitated Radionuclide Transport Modeling in GDSA-PFLOTRAN

Energy Technology Data Exchange (ETDEWEB)

Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-07-31

This report provides documentation of the mathematical basis for a colloid-facilitated radionuclide transport modeling capability that can be incorporated into GDSA-PFLOTRAN. It also provides numerous test cases against which the modeling capability can be benchmarked once the model is implemented numerically in GDSA-PFLOTRAN. The test cases were run using a 1-D numerical model developed by the author, and the inputs and outputs from the 1-D model are provided in an electronic spreadsheet supplement to this report so that all cases can be reproduced in GDSA-PFLOTRAN, and the outputs can be directly compared with the 1-D model. The cases include examples of all potential scenarios in which colloid-facilitated transport could result in the accelerated transport of a radionuclide relative to its transport in the absence of colloids. Although it cannot be claimed that all the model features that are described in the mathematical basis were rigorously exercised in the test cases, the goal was to test the features that matter the most for colloid-facilitated transport; i.e., slow desorption of radionuclides from colloids, slow filtration of colloids, and equilibrium radionuclide partitioning to colloids that is strongly favored over partitioning to immobile surfaces, resulting in a substantial fraction of radionuclide mass being associated with mobile colloids.

Alligator Rivers Analogue project. Radionuclide transport. Final Report - Volume 14

International Nuclear Information System (INIS)

Golian, C.; Lever, D.A.; Baker, A.J.; Connell, L.D.; Bennett, D.G.; Read, D.; Lindgreen, M.; Pers, K.; Skagius, K.; Murakami, T.; Ohnuki, T.

1992-01-01

The Koongarra orebody and its associated dispersion fan are examined as a geological analogue for the transport of radionuclides from waste repositories. The aim is to build a consistent picture of the transport that has been taking place in the orebody and the important processes controlling the retardation of uranium series isotopes and to test models of radionuclide transport. A particularly distinctive feature of the Koongarra system is the strong seasonal dependence of the groundwater flow. However, the Koongarra system is similar to a radioactive waste disposal system in that mobilization of uranium is taking place as a result of the infiltration of groundwaters that are in gross chemical disequilibrium with the mineralogy of the primary ore body. There are considerable differences between the Koongarra uranium orebody and a radioactive waste repository, particularly a deep waste repository. The Koongarra system is shallow, affected by seasonal hydrogeological changes as well as climatic variations on a longer timescale and transport is taking place in a zone of active weathering. Some of these features make the Koongarra system harder to characterise than a deep repository. However, there are nevertheless many analogies between the processes occurring at Koongarra and those occurring around a deep or shallow waste repository. The difficulties encountered because of the heterogeneity of the Koongarra weathered zone mirror those to be addressed in assessing radionuclide transport in repository systems. The 234 U/ 238 U activity ratios in rock samples from the dispersion fan decrease in the direction of groundwater transport, whereas in many other systems it has been reported that 234 U is preferentially mobile relative to 238 U (Osmond and Cowart, 1982; Osmond et al., 1983). As most uranium resides in the rock rather than in the groundwater, the net recoil flux of uranium daughter radionuclides is usually from the rock to the groundwater, thus leading to ( 234

Alligator Rivers Analogue project. Radionuclide transport. Final Report - Volume 14

Energy Technology Data Exchange (ETDEWEB)

Golian, C [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Lever, D A; Baker, A J; Connell, L D [AEA Decommissioning and Radwaste, Harwell (United Kingdom); Bennett, D G; Read, D [WS Atkins Science and Technology Epsom Surrey (United Kingdom); Lindgreen, M; Pers, K; Skagius, K [Kemakta Consultants co., Stockholm (Sweden); Murakami, T; Ohnuki, T [Japan Atomic Energy Research Institute, Tokai-mura, IBARAKI (Japan)

1993-12-31

The Koongarra orebody and its associated dispersion fan are examined as a geological analogue for the transport of radionuclides from waste repositories. The aim is to build a consistent picture of the transport that has been taking place in the orebody and the important processes controlling the retardation of uranium series isotopes and to test models of radionuclide transport. A particularly distinctive feature of the Koongarra system is the strong seasonal dependence of the groundwater flow. However, the Koongarra system is similar to a radioactive waste disposal system in that mobilization of uranium is taking place as a result of the infiltration of groundwaters that are in gross chemical disequilibrium with the mineralogy of the primary ore body. There are considerable differences between the Koongarra uranium orebody and a radioactive waste repository, particularly a deep waste repository. The Koongarra system is shallow, affected by seasonal hydrogeological changes as well as climatic variations on a longer timescale and transport is taking place in a zone of active weathering. Some of these features make the Koongarra system harder to characterise than a deep repository. However, there are nevertheless many analogies between the processes occurring at Koongarra and those occurring around a deep or shallow waste repository. The difficulties encountered because of the heterogeneity of the Koongarra weathered zone mirror those to be addressed in assessing radionuclide transport in repository systems. The {sup 234}U/{sup 238}U activity ratios in rock samples from the dispersion fan decrease in the direction of groundwater transport, whereas in many other systems it has been reported that {sup 234}U is preferentially mobile relative to {sup 238}U (Osmond and Cowart, 1982; Osmond et al., 1983). As most uranium resides in the rock rather than in the groundwater, the net recoil flux of uranium daughter radionuclides is usually from the rock to the groundwater

Alligator Rivers Analogue project. Radionuclide transport. Final Report - Volume 14

Energy Technology Data Exchange (ETDEWEB)

Golian, C. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Lever, D.A.; Baker, A.J.; Connell, L.D. [AEA Decommissioning and Radwaste, Harwell (United Kingdom); Bennett, D.G.; Read, D. [WS Atkins Science and Technology Epsom Surrey (United Kingdom); Lindgreen, M.; Pers, K.; Skagius, K. [Kemakta Consultants co., Stockholm (Sweden); Murakami, T.; Ohnuki, T. [Japan Atomic Energy Research Institute, Tokai-mura, IBARAKI (Japan)

1992-12-31

The Koongarra orebody and its associated dispersion fan are examined as a geological analogue for the transport of radionuclides from waste repositories. The aim is to build a consistent picture of the transport that has been taking place in the orebody and the important processes controlling the retardation of uranium series isotopes and to test models of radionuclide transport. A particularly distinctive feature of the Koongarra system is the strong seasonal dependence of the groundwater flow. However, the Koongarra system is similar to a radioactive waste disposal system in that mobilization of uranium is taking place as a result of the infiltration of groundwaters that are in gross chemical disequilibrium with the mineralogy of the primary ore body. There are considerable differences between the Koongarra uranium orebody and a radioactive waste repository, particularly a deep waste repository. The Koongarra system is shallow, affected by seasonal hydrogeological changes as well as climatic variations on a longer timescale and transport is taking place in a zone of active weathering. Some of these features make the Koongarra system harder to characterise than a deep repository. However, there are nevertheless many analogies between the processes occurring at Koongarra and those occurring around a deep or shallow waste repository. The difficulties encountered because of the heterogeneity of the Koongarra weathered zone mirror those to be addressed in assessing radionuclide transport in repository systems. The {sup 234}U/{sup 238}U activity ratios in rock samples from the dispersion fan decrease in the direction of groundwater transport, whereas in many other systems it has been reported that {sup 234}U is preferentially mobile relative to {sup 238}U (Osmond and Cowart, 1982; Osmond et al., 1983). As most uranium resides in the rock rather than in the groundwater, the net recoil flux of uranium daughter radionuclides is usually from the rock to the groundwater

Radionuclide transport report for the safety assessment SR-Site

Energy Technology Data Exchange (ETDEWEB)

2010-12-15

This document compiles radionuclide transport calculations of a KBS-3 repository for the safety assessment SR-Site. The SR-Site assessment supports the licence application for a final repository at Forsmark, Sweden

Uncertainties in geologic disposal of high-level wastes - groundwater transport of radionuclides and radiological consequences

International Nuclear Information System (INIS)

Kocher, D.C.; Sjoreen, A.L.; Bard, C.S.

1983-01-01

The analysis for radionuclide transport in groundwater considers models and methods for characterizing (1) the present geologic environment and its future evolution due to natural geologic processes and to repository development and waste emplacement, (2) groundwater hydrology, (3) radionuclide geochemistry, and (4) the interactions among these phenomena. The discussion of groundwater transport focuses on the nature of the sources of uncertainty rather than on quantitative estimates of their magnitude, because of the lack of evidence that current models can provide realistic quantitative predictions of radionuclide transport in groundwater for expected repository environments. The analysis for the long-term health risk to man following releases of long-lived radionuclides to the biosphere is more quantitative and involves estimates of uncertainties in (1) radionuclide concentrations in man's exposure environment, (2) radionuclide intake by exposed individuals per unit concentration in the environment, (3) the dose per unit intake, (4) the number of exposed individuals, and (5) the health risk per unit dose. For the important long-lived radionuclides in high-level waste, uncertainties in most of the different components of a calculation of individual and collective dose per unit release appear to be no more than two or three orders of magnitude; these uncertainties are certainly much less than uncertainties in predicting groundwater transport of radionuclides between a repository and the biosphere. Several limitations in current models for predicting the health risk to man per unit release to the biosphere are discussed

Radionuclide transport in the repository near-field and far-field

International Nuclear Information System (INIS)

Poteri, A.; Nordman, H.; Pulkkanen, V.-M.; Smith, P.

2014-01-01

This report is a background report of the TURVA-2012 safety case report 'Assessment of Radionuclide Release Scenarios for the Repository System'. This report gives a comprehensive account of the modelling of radionuclide release from a defective canister and the subsequent migration to the surface groundwater system. The focus of this report is in the radionuclide migration both in the repository near-field and in the repository far-field. Radionuclide releases from the canister and migration through the repository near-field and far-field have also been analysed in the probabilistic sensitivity analysis based on the Monte Carlo simulation method. Those simulations are discussed in a separate report by Cormenzana. Calculation cases are derived from three different types of scenarios: (i) The base scenario that assumes a single initially defective canister located in a cautiously selected canister position, i.e. selecting the failed canister location such that radionuclide release and transport properties are conservative compared to the statistics over all canister locations. Migration processes and parameter values follow the most likely lines of evolution. Repository safety functions are assumed to perform according to the design basis. Calculation cases defined in the Assessment of Radionuclide Release Scenarios report are also supplemented by additional calculation cases that are aimed to study variability between different DFN realisations (additional BS-ALL cases), longitudinal dispersion (BS-RC-ld cases) and alternative realisations of the transport classes along the release paths (BS-RC-tc cases), (ii) Variant scenarios that study declined performance of the repository safety functions. These include enhanced corrosion failure and degradation of the buffer under variant geochemical conditions (iii) Disturbance scenarios that analyse influences of unlikely events on the radionuclide release and migration. Analysis of the variant and disturbance scenarios

A study on the radionuclide transport through fractured porous media based on the network resistance model

International Nuclear Information System (INIS)

Hwang, Ki Ha

2000-02-01

Before the actual construction of radioactive waste repository, analysis of radionuclide transport is required to predict the radiological effect on public and environment. Many models have been developed to predict the realistic radionuclide transport through the repository. In this study, Network Resistance Model (NRM) that is similar to electrical circuit network is adopted to simulate the radionuclide transport. NRM assume the media of repository as the resistance of the radionuclide transport and describes the transport phenomena of radionuclide by connecting the resistance as network. NRM is easy to apply to describe complex system and take less calculation time compared to the other model. The object of this study is to develop the fast, simple and efficient calculation method to simulate the radionuclide with the newly adopted concept using network resistance. New system configuration specially focused on rock edge region is introduced by dividing the rock matrix. By dividing the rock edge from the main rock matrix region, the rock edge region is more carefully analyzed and compared. Rock edge region can accelerate radionuclide transport due to the reducing effect on the total resistivity of rock matrix. Therefore, increased radioactive dose is expected when we apply NRM methodology in the performance assessment of the repository. Result of the performance assessment can be more conservative and reliable. NRM can be applied to other system configuration and for more complex pathways. NRM is simple to us e and easy to modify than any other modeling method

Development of COLLAGE 3; Role for colloids in the transport of radionuclides

Energy Technology Data Exchange (ETDEWEB)

Klos, Richard (Aleksandria Sciences, Sheffield (United Kingdom)); Bath, Adrian (Intellisci Ltd., Loughborough (United Kingdom))

2010-03-15

The issue of colloid-facilitated radionuclide transport (CFRT) was last addressed by the Swedish nuclear regulators in 2001 - 2002. SKI had commissioned the Collage code with subsequent development as Collage 2. This code was employed to investigate the potential role for colloids to have been involved in the transport of radionuclides at the Nevada Test Site and to examine the implications for CFRT in the Swedish disposal programme. It was concluded that colloids could not be ruled out as a mechanism for rapid transport and early release from the geosphere. Recently the 'bentonite erosion scenario' has become of concern. In it the generation of large quantities of bentonite colloids in fractures as a result of fresh water ingress at repository depth is possible. Potentially, these could carry radiologically significant quantities of radionuclides to an early release to the surface system. The objectives of this work are to update the knowledge of colloid-facilitated radionuclide transport through a fractured geosphere and to provide review capability within the SSM. Recent developments in CFRT (reviewed here) indicate that additional parameters needed to be added to the existing Collage 2 plus code in order to adequately represent colloid transport in fractures. This report looks at modifications to the model and discusses the implications of the implementation of the new processes. Authors conclude that the process of colloid filtration is an important mitigating mechanism. A new code - Collage 3 - is demonstrated and suggestions for further work are given

Monitoring and characterization of radionuclide transport in the hydrogeologic system

International Nuclear Information System (INIS)

Phillips, S.J.; Raymond, J.R.

1975-01-01

The groundwater monitoring program provides information and data on groundwater quality required to evaluate the impact of waste disposal practices on the Hanford Reservation. The program includes: collection and analysis of groundwater samples on a routine basis; data processing, analysis and reporting; design, construction and maintenance of well sampling structures; and design and implementation of supporting research studies. Within the overall framework of the Groundwater Monitoring Program, the 300 Area and Wye Burial Ground Characterization Program was initiated to evaluate transport of radionuclides in the partially saturated zone above the water table and to provide site characterization at solid waste burial locations on the Reservation. Methods for collecting and analyzing program data include geophysical exploration by ground penetrating radar, refraction and reflection acoustics, magnetics, and metal detection; stratigraphic investigations by drilling and sample collection techniques; evaluation of transport phenomena by in situ psychrometric and gamma-neutron techniques; laboratory characterization of fluid and vapor transport-controlling mechanisms; and evaluation of biological radionuclide transport by organisms inhabiting contaminated areas

The Influence of Fractures on Radionuclide Transport in Granite Formations

International Nuclear Information System (INIS)

Guarracino, Luis; Quintana, Fernando; Bevilacqua, Arturo

2003-01-01

Simulation of radionuclide transport in fractured hard rocks is of interest to many research areas like geological disposal of high-level nuclear wastes.The objective of this study is to present a numerical simulation of water flow and radionuclide transport near a hypothetical repository in deep geological formations.The water flow is assumed to obey the highly nonlinear Richards' equation, which is approximated using a finite element method for the spatial discretization combined with a third order accurate Crank-Nicholson scheme in time.A Picard iteration scheme is used to treat the non-linear terms of the equation.Contaminant transport is described by the advection-diffusion-reaction equation, assuming linear adsorption and first order decay.This equation is solved using a Sub Grid Scale algorithm.Illustrative examples showing the influence of fractures in the contaminant process for different radioisotopes are presented

Theoretical background and user's manual for the computer code on groundwater flow and radionuclide transport calculation in porous rock

International Nuclear Information System (INIS)

Shirakawa, Toshihiko; Hatanaka, Koichiro

2001-11-01

In order to document a basic manual about input data, output data, execution of computer code on groundwater flow and radionuclide transport calculation in heterogeneous porous rock, we investigated the theoretical background about geostatistical computer codes and the user's manual for the computer code on groundwater flow and radionuclide transport which calculates water flow in three dimension, the path of moving radionuclide, and one dimensional radionuclide migration. In this report, based on above investigation we describe the geostatistical background about simulating heterogeneous permeability field. And we describe construction of files, input and output data, a example of calculating of the programs which simulates heterogeneous permeability field, and calculates groundwater flow and radionuclide transport. Therefore, we can document a manual by investigating the theoretical background about geostatistical computer codes and the user's manual for the computer code on groundwater flow and radionuclide transport calculation. And we can model heterogeneous porous rock and analyze groundwater flow and radionuclide transport by utilizing the information from this report. (author)

Handling Interfaces and Time-varying Properties in Radionuclide Transport Models

International Nuclear Information System (INIS)

Robinson, Peter; Watson, Claire

2010-12-01

This report documents studies undertaken by Quintessa during 2010 in preparation for the SR-Site review that will be initiated by SSM in 2011. The studies relate to consequence analysis calculations, that is to the calculation of radionuclide release and transport if a canister is breached. A sister report documents modelling work undertaken to investigate the coupled processes relevant to copper corrosion and buffer erosion. The Q eq concept is an important part of SKB's current methodology for radionuclide transport using one-dimensional transport modelling; it is used in particular to model transport at the buffer/fracture interface. Quintessa's QPAC code has been used to investigate the Q eq approach and to explore the importance of heterogeneity in the fracture and spalling on the deposition hole surface. The key conclusions are that: - The basic approach to calculating Q eq values is sound and can be reproduced in QPAC. - The fracture resistance dominates over the diffusive resistance in the buffer except for the highest velocity cases. - Heterogeneity in the fracture, in terms of uncorrelated random variations in the fracture aperture, tends to reduce releases, so the use of a constant average aperture approach is conservative. - Narrow channels could lead to the same release as larger fractures with the same pore velocity, so a channel enhancement factor of √10 should be considered. - A spalling zone that increases the area of contact between flowing water and the buffer has the potential to increase the release significantly and changes the functional dependence of Q eq frac on the flowing velocity. Quintessa's AMBER software has previously been used to reproduce SKB's one-dimensional transport calculations and AMBER allows the use of time varying properties. This capability has been used to investigate the effects of glacial episodes on radionuclide transport. The main parameters that could be affected are sorption coefficients and flow rates. For both

Handling Interfaces and Time-varying Properties in Radionuclide Transport Models

Energy Technology Data Exchange (ETDEWEB)

Robinson, Peter; Watson, Claire (Quintessa Ltd., Henley-on-Thames (United Kingdom))

2010-12-15

This report documents studies undertaken by Quintessa during 2010 in preparation for the SR-Site review that will be initiated by SSM in 2011. The studies relate to consequence analysis calculations, that is to the calculation of radionuclide release and transport if a canister is breached. A sister report documents modelling work undertaken to investigate the coupled processes relevant to copper corrosion and buffer erosion. The Q{sub eq} concept is an important part of SKB's current methodology for radionuclide transport using one-dimensional transport modelling; it is used in particular to model transport at the buffer/fracture interface. Quintessa's QPAC code has been used to investigate the Q{sub eq} approach and to explore the importance of heterogeneity in the fracture and spalling on the deposition hole surface. The key conclusions are that: - The basic approach to calculating Q{sub eq} values is sound and can be reproduced in QPAC. - The fracture resistance dominates over the diffusive resistance in the buffer except for the highest velocity cases. - Heterogeneity in the fracture, in terms of uncorrelated random variations in the fracture aperture, tends to reduce releases, so the use of a constant average aperture approach is conservative. - Narrow channels could lead to the same release as larger fractures with the same pore velocity, so a channel enhancement factor of sq root10 should be considered. - A spalling zone that increases the area of contact between flowing water and the buffer has the potential to increase the release significantly and changes the functional dependence of Q{sub eq}frac on the flowing velocity. Quintessa's AMBER software has previously been used to reproduce SKB's one-dimensional transport calculations and AMBER allows the use of time varying properties. This capability has been used to investigate the effects of glacial episodes on radionuclide transport. The main parameters that could be affected are

Chancellor Water Colloids: Characterization and Radionuclide Associated Transport

Energy Technology Data Exchange (ETDEWEB)

Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Boukhalfa, Hakim [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-09-26

Column transport experiments were conducted in which water from the Chancellor nuclear test cavity was transported through crushed volcanic tuff from Pahute Mesa. In one experiment, the cavity water was spiked with solute ¹³⁷Cs, and in another it was spiked with ^239/240Pu(IV) nanocolloids. A third column experiment was conducted with no radionuclide spike at all, although the ¹³⁷Cs concentrations in the water were still high enough to quantify in the column effluent. The radionuclides strongly partitioned to natural colloids present in the water, which were characterized for size distribution, mass concentration, zeta potential/surface charge, critical coagulation concentration, and qualitative mineralogy. In the spiked water experiments, the unanalyzed portion of the high-concentration column effluent samples were combined and re-injected into the respective columns as a second pulse. This procedure was repeated again for a third injection. Measurable filtration of the colloids was observed after each initial injection of the Chancellor water into the columns, but the subsequent injections (spiked water experiments only) exhibited no apparent filtration, suggesting that the colloids that remained mobile after relatively short transport distances were more resistant to filtration than the initial population of colloids. It was also observed that while significant desorption of ¹³⁷Cs from the colloids occurred after the first injection in both the spiked and unspiked waters, subsequent injections of the spiked water exhibited much less ¹³⁷Cs desorption (much greater ¹³⁷Cs colloid-associated transport). This result suggests that the ¹³⁷Cs that remained associated with colloids during the first injection represented a fraction that was more strongly adsorbed to the mobile colloids than the initial ¹³⁷Cs associated with the colloids. A greater amount of the ^239/240

Radionuclide transport through heteogeneous media

International Nuclear Information System (INIS)

Hadermann, J.

1980-01-01

One-dimensional radionuclide migration for conevective water transport with sorption and longitudinal dispersion is investigated. A semianalytic solution for layered media with piecewise constant parametes can be written when taking into account mass conservation and approximate flux conservation at interlayer boundaries. The solution is analytic in the first layer and allows for a recursive calculation in the following layers. Scaling laws for the relevant parameters can be formulated. Numerical examples exhibit the importance of at least a single highly sorbing layer. Small values of dispersivity may not lead to a conservative estimate of conservation at the geological column's end

Los ensueños en terapia gestáltica

Directory of Open Access Journals (Sweden)

Francisco Vásquez

2003-06-01

Full Text Available Se describe el ensueño a través de los tiempos y el significado que tiene y tuvo según las épocas y las culturas. Se enfoca la teoría general de los ensueños desde Hipócrates hasta nuestros días, así como su interpretación, tanto del punto de vista psicológico como religioso y cultural. Se hace énfasis en la función terapéutica de los ensueños, tanto en la terapia freudiana como la jungiana y la gestáltica. Reflexiona sobre los aportes de Freud, Jung y Perls, ampliando los conceptos del ensueño de la terapia gestáltica, que considera el ensueño "como el camino real a la integración, siendo la producción humana más espontánea de la existencia. El ensueño es la expresión que nos llega sin intención, voluntad y deseo. El ensueño más absurdo no nos impacta en el mismo momento como algo absurdo, se siente como verdadero. El ensueño es mucho más que un deseo inconcluso, es un mensaje existencial muy claro acerca de lo que falta en nuestras vidas, lo que se evita hacer y vivir". Se ilustra el ensayo con un trabajo de ensueño con una paciente en la Clínica de Día, del Hospital Guillermo Almenara, empleando las técnicas gestálticas. El ensayo se circunscribe a una apreciación de la filosofía y praxis gestáltica sobre los ensueños.

Effects of bedrock fractures on radionuclide transport near a vertical deposition hole for spent nuclear fuel

International Nuclear Information System (INIS)

Pulkkanen, V.-M.; Nordman, H.

2011-12-01

Effects of bedrock fractures on radionuclide transport near a vertical deposition hole for spent nuclear fuel are studied computationally. The studied fractures are both natural and excavation damage fractures. The emphasis is on the detailed modelling of geometry in 3D in contrast to the traditional radionuclide transport studies that often concentrate on chain decays, sorption, and precipitation at the expense of the geometry. The built computer model is used to assess the significance of components near a deposition hole for radionuclide transport and to estimate the quality of previously used modelling techniques. The results show nearly exponential decrease of radionuclide mass in the bentonite buffer when the release route is a thin natural fracture. The results also imply that size is the most important property of the tunnel section for radionuclide transport. In addition, the results demonstrate that the boundary layer theory can be used to approximate the release of radionuclides with certain accuracy and that a thin fracture in rock can be modelled, at least to a certain limit, by using a fracture with wider aperture but with same flow rate as the thin fracture. (orig.)

Development and testing of radionuclide transport models for fractured crystalline rock. An overview of the Nagra/JNC radionuclide retardation programme

International Nuclear Information System (INIS)

Ota, Kunio; Alexander, W.R.

2001-01-01

The joint Nagra/JNC radionuclide Retardation Programme has now been ongoing for more thean 10 years with the main aim of direct testing of radionuclide transport models for fractured crystalline rocks in as realistic a manner as possible. A large programme of field, laboratory and natural analogue studies has been carried out at the Grimsel Test Site in the central Swiss Alps. The understanding and modelling of both the processes and the structures influencing radionuclide transport in fractured crystalline rocks have matured as has the experimental technology, which has contributed to develop confidence in the applicability of the underlying research models in a repository performance assessment. In this report, the successes and set-backs of this programme are discussed as is the general approach to the thorough testing of the process models and of model assumptions. (author)

Effects of macropores on groundwater flow and transport of radionuclides

International Nuclear Information System (INIS)

Huff, D.D.; DeAngelis, D.L.; Yeh, G.T.

1983-01-01

In humid environments, recent findings have shown that an important component of runoff and associated solute moves rapidly through large continuous voids. Thus, consideration of radionuclide transport in subsurface flow is incomplete without explicit treatment of continuous macropores and interaction between macropore flow and the soil matrix. A computer model, FRACPORT, that simulates the transport of a solute through a fractured porous matrix has been developed. The model employs the Integrated Compartment Method and uses the approach of dividing the porous media into compartments comprising fractures or porous material. The fracture region and a small portion of the porous matrix are simulated using a shorter time step than for the remaining porous matrix. This allows substantial savings in computational time. The model should be useful for analyses of generic problems associated with water and radionuclide transport in macropore systems at shallow-land disposal sites in humid environments. 14 references, 6 figures, 1 table

Quantification of glacial effects on radionuclide transport: transport sensitivity studies for SKI's SITE-94

International Nuclear Information System (INIS)

King-Clayton, L.M.; Smith, P.A.; Dverstorp, B.

1996-01-01

Site-scale radionuclide transport calculations have been carried out for a hypothetical deep repository at the Aespoe site, southeast Sweden. The work complements and utilizes results from regional-scale, variable density flow modelling in which the groundwater flow field is time-dependent, reflecting the impact of climate evolution over the next 130,000 years at the site. The climate evolution and its impacts are qualitatively described in the Central Climate Change Scenario, which specifies a hypothetical evolution of the local climate over the period modelled, including the periodic development of permafrost conditions and ice sheet advance and retreat. The work summarised here is complementary to the transport calculations undertaken as part of the SKI SITE-94 performance assessment project, with the specific objective of quantifying the impact of transient changes in flow direction and magnitude. The spatial evolution of 79 Se and 129 I contaminant plumes, released from the hypothetical repository under the influence of time-dependent (step-wise varying) head boundary conditions associated with ice sheet and permafrost development, is compared with that of a steady-state Base Case based on continuing present-day conditions. The results indicate that temporal changes in flow conditions due to future climate changes can have a significant effect on the transport of radionuclides from a source at depth. A case with high sub-ice sheet recharge and taliks (ie. gaps in the permafrost), creating groundwater fluxes up to an order of magnitude greater than the Base Case, has the greatest impact on radionuclide flux out of the geosphere, with a maximum 79 Se flux of over three orders of magnitude greater than that of the Base Case. The maximum 129 I flux is nearer one order of magnitude greater than the Base Case. In all cases modelled with time dependent boundary conditions, the greatest radionuclide fluxes occur towards the end of the main glacial periods (periods

Transport of Gas Phase Radionuclides in a Fractured, Low-Permeability Reservoir

Science.gov (United States)

Cooper, C. A.; Chapman, J.

2001-12-01

The U.S. Atomic Energy Commission (predecessor to the Department of Energy, DOE) oversaw a joint program between industry and government in the 1960s and 1970s to develop technology to enhance production from low-permeability gas reservoirs using nuclear stimulation rather than conventional means (e.g., hydraulic and/or acid fracturing). Project Rio Blanco, located in the Piceance Basin, Colorado, was the third experiment under the program. Three 30-kiloton nuclear explosives were placed in a 2134 m deep well at 1780, 1899, and 2039 m below the land surface and detonated in May 1973. Although the reservoir was extensively fractured, complications such as radionuclide contamination of the gas prevented production and subsequent development of the technology. Two-dimensional numerical simulations were conducted to identify the main transport processes that have occurred and are currently occurring in relation to the detonations, and to estimate the extent of contamination in the reservoir. Minor modifications were made to TOUGH2, the multiphase, multicomponent reservoir simulator developed at Lawrence Berkeley National Laboratories. The simulator allows the explicit incorporation of fractures, as well as heat transport, phase change, and first order radionuclide decay. For a fractured two-phase (liquid and gas) reservoir, the largest velocities are of gases through the fractures. In the gas phase, tritium and one isotope of krypton are the principle radionuclides of concern. However, in addition to existing as a fast pathway, fractures also permit matrix diffusion as a retardation mechanism. Another retardation mechanism is radionuclide decay. Simulations show that incorporation of fractures can significantly alter transport rates, and that radionuclides in the gas phase can preferentially migrate upward due to the downward gravity drainage of liquid water in the pores. This project was funded by the National Nuclear Security Administration, Nevada Operations Office

Assessment of hydrologic transport of radionuclides from the Rio Blanco underground nuclear test site, Colorado

International Nuclear Information System (INIS)

Chapman, J.; Earman, S.; Andricevic, R.

1996-10-01

DOE is operating an environmental restoration program to characterize, remediate, and close non-Nevada Test Site locations used for nuclear testing. Evaluation of radionuclide transport by groundwater is part of preliminary risk analysis. These evaluations allow prioritization of test areas in terms of risk, provide a basis for discussions with regulators and the public about future work, and provide a framework for assessing site characterization data needs. The Rio Blanco site in Colorado was the location of the simultaneous detonation of three 30-kiloton nuclear devices. The devices were located 1780, 1899, and 2039 below ground surface in the Fort Union and Mesaverde formations. Although all the bedrock formations at the site are thought to contain water, those below the Green River Formation (below 1000 in depth) are also gas-bearing, and have very low permeabilities. The transport scenario evaluated was the migration of radionuclides from the blast-created cavity through the Fort Union Formation. Transport calculations were performed using the solute flux method, with input based on the limited data available for the site. Model results suggest that radionuclides from the test are contained entirely within the area currently administered by DOE. This modeling was performed to investigate how the uncertainty in various physical parameters affect radionuclide transport at the site, and to serve as a starting point for discussion regarding further investigation; it was not intended to be a definitive simulation of migration pathways or radionuclide concentration values. Given the sparse data, the modeling results may differ significantly from reality. Confidence in transport predictions can be increased by obtaining more site data, including the amount of radionuclides which would have been available for transport (i.e., not trapped in melt glass or vented during gas flow testing), and the hydraulic properties of the formation. 38 refs., 6 figs., 1 tab

GIS Modelling of Radionuclide Transport from the Semipalatinsk Test Site

Science.gov (United States)

Balakay, L.; Zakarin, E.; Mahura, A.; Baklanov, A.; Sorensen, J. H.

2009-04-01

In this study, the software complex GIS-project MigRad (Migration of Radionuclide) was developed, tested and applied for the territory of the Semipalatinsk test site/ polygon (Republic of Kazakhstan), where since 1961, in total 348 underground nuclear explosions were conducted. The MigRad is oriented on integration of large volumes of different information (mapping, ground-based, and satellite-based survey): and also includes modeling on its base local redistribution of radionuclides by precipitation and surface waters and by long-range transport of radioactive aerosols. The existing thermal anomaly on territory of the polygon was investigated in details, and the object-oriented analysis was applied for the studied area. Employing the RUNOFF model, the simulation of radionuclides migration with surface waters was performed. Employing the DERMA model, the simulation of long-term atmospheric transport, dispersion and deposition patterns for cesium was conducted from 3 selected locations (Balapan, Delegen, and Experimental Field). Employing geoinformation technology, the mapping of the of the high temperature zones and epicenters of radioactive aerosols transport for the territory of the test site was carried out with post-processing and integration of modelling results into GIS environment. Contamination levels of pollution due to former nuclear explosions for population and environment of the surrounding polygon territories of Kazakhstan as well as adjacent countries were analyzed and evaluated. The MigRad was designed as instrument for comprehensive analysis of complex territorial processes influenced by former nuclear explosions on the territory of Semipalatinsk test site. It provides possibilities in detailed analyses for (i) extensive cartographic material, remote sensing, and field measurements data collected in different level databases; (ii) radionuclide migration with flows using accumulation and redistribution of soil particles; (iii) thermal anomalies

Evaluating biological transport of radionuclides at low-level waste burial sites

International Nuclear Information System (INIS)

Cadwell, L.L.; Kennedy, W.E.; McKenzie, D.H.

1983-08-01

The purpose of the work reported here is to develop and demonstrate methods for evaluating the long-term impact of biological processes at low-level waste (LLW) disposal sites. As part of this effort, we developed order-of-magnitude estimates of dose-to-man resulting from animal burrowing activity and plant translocation of radionuclides. Reference low-level waste sites in both arid and humid areas of the United States were examined. The results of our evaluation for generalized arid LLW burial site are presented here. Dose-to-man estimates resulting from biotic transport are compared with doses calculated from human intrusion exposure scenarios. Dose-to-man estimates, as a result of biotic transport, are of the same order of magnitude as those resulting from a more commonly evaluated human intrusion scenario. The reported lack of potential importance of biotic transport at LLW sites in earlier assessment studies is not confirmed by our findings. These results indicate that biotic transport has the long-term potential to mobilize radionuclides. Therefore, biotic transport should be carefully evaluated during burial site assessment

Fundamental approach to the analysis of radionuclide transport resulting from fluid flow through jointed media

International Nuclear Information System (INIS)

Erickson, K.L.

1981-02-01

A theoretical and experimental basis is being developed for analysis of radionuclide transport in jointed geologic media. Batch equilibration and rate experiments involving samples of Eleana argillite and Tertiary silicic tuffs in contact with solutions containing Cs, Sr or Pm indicated that most radionuclide sorption is associated with the surfaces of very small intergranular regions and that the rate of sorption is controlled by diffusion of the nuclides into such regions. Based on these experimental results, the continuity equations for radionuclides in the mobile and immobile phases were reduced to a model analogous to Rosen's equations for packed beds and were solved similarly to Rosen's solutions. Using the model and experimental data, limited radionuclide transport analyses were made which indicated that important parameters controlling transport include the intergranular porosity and nuclide penetration depth, fracture plate spacing and length, fluid velocity, and sorption distribution coefficient

Sorption-capacity limited retardation of radionuclides transport in water-saturated packing materials

International Nuclear Information System (INIS)

Pescatore, C.; Sullivan, T.

1984-01-01

Radionuclides breakthrough times as calculated through constant retardation factors obtained in dilute solutions are non-conservative. The constant retardation approach regards the solid as having infinite sorption capacity throughout the solid. However, as the solid become locally saturated, such as in the proximity of the waste form-packing materials interface, it will exhibit no retardation properties, and transport will take place as if the radionuclides were locally non-reactive. The magnitude of the effect of finite sorption capacity of the packing materials on radionuclide transport is discussed with reference to high-level waste package performance. An example based on literature sorption data indicated that the breakthrough time may be overpredicted by orders of magnitude using a constant retardation factor as compared to using the entire sorption isotherm to obtain a concentration-dependent retardation factor. 8 refs., 3 figs., 3 tabs

Sorption-capacity limited retardation of radionuclides transport in water-saturated packing materials

International Nuclear Information System (INIS)

Pescatore, C.; Sullivan, T.

1984-01-01

Radionuclides breakthrough times as calculated through constant retardation factors obtained in dilute solutions are non-conservative. The constant retardation approach regards the solid as having infinite sorption capacity throughout the solid. However, as the solid becomes locally saturated, such as in the proximity of the waste form-packing materials interface, it will exhibit no retardation properties, and transport will take place as if the radionuclides were locally non-reactive. The magnitude of the effect of finite sorption capacity of the packing materials on radionuclide transport is discussed with reference to high-level waste package performance. An example based on literature sorption data indicates that the breakthrough time may be overpredicted by orders of magnitude using a constant retardation factor as compared to using the entire sorption isotherm to obtain a concentration-dependent retardation factor. 8 references, 3 figures, 3 tables

MATADOR (Methods for the Analysis of Transport And Deposition Of Radionuclides) code description and User's Manual

International Nuclear Information System (INIS)

Avci, H.I.; Raghuram, S.; Baybutt, P.

1985-04-01

A new computer code called MATADOR (Methods for the Analysis of Transport And Deposition Of Radionuclides) has been developed to replace the CORRAL-2 computer code which was written for the Reactor Safety Study (WASH-1400). This report is a User's Manual for MATADOR. MATADOR is intended for use in system risk studies to analyze radionuclide transport and deposition in reactor containments. The principal output of the code is information on the timing and magnitude of radionuclide releases to the environment as a result of severely degraded core accidents. MATADOR considers the transport of radionuclides through the containment and their removal by natural deposition and by engineered safety systems such as sprays. It is capable of analyzing the behavior of radionuclides existing either as vapors or aerosols in the containment. The code requires input data on the source terms into the containment, the geometry of the containment, and thermal-hydraulic conditions in the containment

The impacts of pore-scale physical and chemical heterogeneities on the transport of radionuclide-carrying colloids

Energy Technology Data Exchange (ETDEWEB)

WU, Ning

2018-04-24

Independent of the methods of nuclear waste disposal, the degradation of packaging materials could lead to mobilization and transport of radionuclides into the geosphere. This process can be significantly accelerated due to the association of radionuclides with the backfill materials or mobile colloids in groundwater. The transport of these colloids is complicated by the inherent coupling of physical and chemical heterogeneities (e.g., pore space geometry, grain size, charge heterogeneity, and surface hydrophobicity) in natural porous media that can exist on the length scale of a few grains. In addition, natural colloids themselves are often heterogeneous in their surface properties (e.g., clay platelets possess opposite charges on the surface and along the rim). Both physical and chemical heterogeneities influence the transport and retention of radionuclides under various groundwater conditions. However, the precise mechanisms how these coupled heterogeneities influence colloidal transport are largely elusive. This knowledge gap is a major source of uncertainty in developing accurate models to represent the transport process and to predict distribution of radionuclides in the geosphere.

Laboratory studies of radionuclide transport in fractured Climax granite

International Nuclear Information System (INIS)

Failor, R.; Isherwood, D.; Raber, E.; Vandergraaf, T.

1982-06-01

This report documents our laboratory studies of radionuclide transport in fractured granite cores. To simulate natural conditions, our laboratory studies used naturally fractured cores and natural ground water from the Climax Granite Stock at the Nevada Test Site. For comparison, additional tests used artificially fractured granite cores or distilled water. Relative to the flow of tritiated water, 85 Sr and /sup 95m/Tc showed little or no retardation, whereas 137 Cs was retarded. After the transport runs the cores retained varying amounts of the injected radionuclides along the fracture. Autoradiography revealed some correlation between sorption and the fracture fill material. Strontium and cesium retention increased when the change was made from natural ground water to distilled water. Artificial fractures retained less 137 Cs than most natural fractures. Estimated fracture apertures from 18 to 60 μm and hydraulic conductivities from 1.7 to 26 x 10 -3 m/s were calculated from the core measurements

Coupled Transport Phenomena in the Opalinus Clay: Implications for Radionuclide Transport

International Nuclear Information System (INIS)

Soler, J.M.

1999-09-01

Coupled phenomena (thermal and chemical osmosis, hyperfiltration, coupled diffusion, thermal diffusion, thermal filtration, Dufour effect) may play an important role in fluid, solute and heat transport in clay-rich formations, such as the Opalinus Clay (OPA), which are being considered as potential hosts for radioactive waste repositories. In this study, the potential effects of coupled phenomena on radionuclide transport in the vicinity of a repository for vitrified high-level radioactive waste (HLW) and spent nuclear fuel (SF) hosted by the Opalinus Clay, at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years), have been addressed. Firstly, estimates of the solute fluxes associated with chemical osmosis, hyperfiltration, thermal diffusion and thermal osmosis have been calculated. Available experimental data concerning coupled transport phenomena in compacted clays, and the hydrogeological and geochemical conditions to which the Opalinus Clay is subject, have been used for these estimates. These estimates suggest that thermal osmosis is the only coupled transport mechanism that could have a strong impact on solute and fluid transport in the vicinity of the repository. Secondly, estimates of the heat fluxes associated with thermal filtration and the Dufour effect in the vicinity of the repository have been calculated. The calculated heat fluxes are absolutely negligible compared to the heat flux caused by thermal conduction. As a further step to obtain additional insight into the effects of coupled phenomena on solute transport, the solute fluxes associated with advection, chemical diffusion, thermal and chemical osmosis, hyperfiltration and thermal diffusion have been incorporated into a simple one-dimensional transport equation. The analytical solution of this equation, with appropriate parameters, shows again that thermal osmosis is the only coupled transport mechanism that could have a strong effect on repository

Coupled Transport Phenomena in the Opalinus Clay: Implications for Radionuclide Transport

Energy Technology Data Exchange (ETDEWEB)

Soler, J.M.

1999-09-01

Coupled phenomena (thermal and chemical osmosis, hyperfiltration, coupled diffusion, thermal diffusion, thermal filtration, Dufour effect) may play an important role in fluid, solute and heat transport in clay-rich formations, such as the Opalinus Clay (OPA), which are being considered as potential hosts for radioactive waste repositories. In this study, the potential effects of coupled phenomena on radionuclide transport in the vicinity of a repository for vitrified high-level radioactive waste (HLW) and spent nuclear fuel (SF) hosted by the Opalinus Clay, at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years), have been addressed. Firstly, estimates of the solute fluxes associated with chemical osmosis, hyperfiltration, thermal diffusion and thermal osmosis have been calculated. Available experimental data concerning coupled transport phenomena in compacted clays, and the hydrogeological and geochemical conditions to which the Opalinus Clay is subject, have been used for these estimates. These estimates suggest that thermal osmosis is the only coupled transport mechanism that could have a strong impact on solute and fluid transport in the vicinity of the repository. Secondly, estimates of the heat fluxes associated with thermal filtration and the Dufour effect in the vicinity of the repository have been calculated. The calculated heat fluxes are absolutely negligible compared to the heat flux caused by thermal conduction. As a further step to obtain additional insight into the effects of coupled phenomena on solute transport, the solute fluxes associated with advection, chemical diffusion, thermal and chemical osmosis, hyperfiltration and thermal diffusion have been incorporated into a simple one-dimensional transport equation. The analytical solution of this equation, with appropriate parameters, shows again that thermal osmosis is the only coupled transport mechanism that could have a strong effect on repository

CASCADER: An M-chain gas-phase radionuclide transport and fate model

International Nuclear Information System (INIS)

Cawlfield, D.E.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

1993-09-01

Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or dispersion. Additionally during the transport of parent and daughter radionuclides in soil, radionuclide decay may occur. This version of CASCADER called CASCADR9 starts with the concepts presented in volumes one and three of this series. For a proper understanding of how the model works, the reader should read volume one first. Also presented in this volume is a set of realistic scenarios for buried sources of radon gas, and the input and output file structure for CASCADER9

Conceptual model for regional radionuclide transport from a salt dome repository: a technical memorandum

International Nuclear Information System (INIS)

Kier, R.S.; Showalter, P.A.; Dettinger, M.D.

1980-01-01

Disposal of high-level radioactive wastes is a major environmental problem influencing further development of nuclear energy in this country. Salt domes in the Gulf Coast Basin are being investigated as repository sites. A major concern is geologic and hydrologic stability of candidate domes and potential transport of radionuclides by groundwater to the biosphere prior to their degradation to harmless levels of activity. This report conceptualizes a regional geohydrologic model for transport of radionuclides from a salt dome repository. The model considers transport pathways and the physical and chemical changes that would occur through time prior to the radionuclides reaching the biosphere. Necessary, but unknown inputs to the regional model involve entry and movement of fluids through the repository dome and across the dome-country rock interface and the effect on the dome and surrounding strata of heat generated by the radioactive wastes

Conceptual model for regional radionuclide transport from a basalt repository site. Final draft, technical memorandum

International Nuclear Information System (INIS)

Walton, W.C.; Voorhees, M.L.; Prickett, T.A.

1980-01-01

This technical memorandum was prepared to: (1) describe a typical basalt radionuclide repository site, (2) describe geologic and hydrologic processes associated with regional radionuclide transport in basalts, (3) define the parameters required to model regional radionuclide transport from a basalt repository site, and (4) develop a ''conceptual model'' of radionuclide transport from a basalt repository site. In a general hydrological sense, basalts may be described as layered sequences of aquifers and aquitards. The Columbia River Basalt, centered near the semi-arid Pasco Basin, is considered by many to be typical basalt repository host rock. Detailed description of the flow system including flow velocities with high-low hydraulic conductivity sequences are not possible with existing data. However, according to theory, waste-transport routes are ultimately towards the Columbia River and the lengths of flow paths from the repository to the biosphere may be relatively short. There are many physical, chemical, thermal, and nuclear processes with associated parameters that together determine the possible pattern of radionuclide migration in basalts and surrounding formations. Brief process descriptions and associated parameter lists are provided. Emphasis has been placed on the use of the distribution coefficient in simulating ion exchange. The use of the distribution coefficient approach is limited because it takes into account only relatively fast mass transfer processes. In general, knowledge of hydrogeochemical processes is primitive

Conceptual model for regional radionuclide transport from a basalt repository site. Final draft, technical memorandum

Energy Technology Data Exchange (ETDEWEB)

Walton, W.C.; Voorhees, M.L.; Prickett, T.A.

1980-05-23

This technical memorandum was prepared to: (1) describe a typical basalt radionuclide repository site, (2) describe geologic and hydrologic processes associated with regional radionuclide transport in basalts, (3) define the parameters required to model regional radionuclide transport from a basalt repository site, and (4) develop a ''conceptual model'' of radionuclide transport from a basalt repository site. In a general hydrological sense, basalts may be described as layered sequences of aquifers and aquitards. The Columbia River Basalt, centered near the semi-arid Pasco Basin, is considered by many to be typical basalt repository host rock. Detailed description of the flow system including flow velocities with high-low hydraulic conductivity sequences are not possible with existing data. However, according to theory, waste-transport routes are ultimately towards the Columbia River and the lengths of flow paths from the repository to the biosphere may be relatively short. There are many physical, chemical, thermal, and nuclear processes with associated parameters that together determine the possible pattern of radionuclide migration in basalts and surrounding formations. Brief process descriptions and associated parameter lists are provided. Emphasis has been placed on the use of the distribution coefficient in simulating ion exchange. The use of the distribution coefficient approach is limited because it takes into account only relatively fast mass transfer processes. In general, knowledge of hydrogeochemical processes is primitive.

Models for transport and fate of carbon, nutrients and point source released radionuclides to an aquatic ecosystem

Energy Technology Data Exchange (ETDEWEB)

Kumblad, Linda [Stockholm Univ. (Sweden). Dept. of Systems Ecology; Kautsky, Ulrik [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

2004-09-01

In this report three ecosystem models are described in terms of structure, initial data, and results. All models are dynamic, mass-balanced and describe the transport and fate of elements in an open aquatic ecosystem. The models are based on ecologically sound principles, provide model results with high resolution and transparency, and are constrained by the nutrient dynamics of the ecosystem itself. The processes driving the transport in all the models are both the biological processes such as primary production, consumption, respiration and excretion, and abiotic e.g. water exchange and air-sea exchange. The first model, the CNP-model, describes the distribution and fluxes of carbon and nutrients for the coastal ecosystem off Forsmark. The second model, the C-14 model, is an extension of the CNP-model and describes the transport and distribution of hypothetically released C-14 from the underground repository SFR-1 to the ecosystem above. The third model, the RN-model, is a generic radionuclide flow model that models the transport and distribution of radionuclides other than C-14 hypothetically discharged to the ecosystem. The model also analyses the importance of some radionuclide specific mechanisms for the radionuclide flow. The generic radionuclide model is also based on the CNP-model, but has radionuclide specific mechanisms connected to each compartment.

Models for transport and fate of carbon, nutrients and point source released radionuclides to an aquatic ecosystem

International Nuclear Information System (INIS)

Kumblad, Linda

2004-09-01

In this report three ecosystem models are described in terms of structure, initial data, and results. All models are dynamic, mass-balanced and describe the transport and fate of elements in an open aquatic ecosystem. The models are based on ecologically sound principles, provide model results with high resolution and transparency, and are constrained by the nutrient dynamics of the ecosystem itself. The processes driving the transport in all the models are both the biological processes such as primary production, consumption, respiration and excretion, and abiotic e.g. water exchange and air-sea exchange. The first model, the CNP-model, describes the distribution and fluxes of carbon and nutrients for the coastal ecosystem off Forsmark. The second model, the C-14 model, is an extension of the CNP-model and describes the transport and distribution of hypothetically released C-14 from the underground repository SFR-1 to the ecosystem above. The third model, the RN-model, is a generic radionuclide flow model that models the transport and distribution of radionuclides other than C-14 hypothetically discharged to the ecosystem. The model also analyses the importance of some radionuclide specific mechanisms for the radionuclide flow. The generic radionuclide model is also based on the CNP-model, but has radionuclide specific mechanisms connected to each compartment

Preliminary integrated calculation of radionuclide cation and anion transport at Yucca Mountain using a geochemical model

International Nuclear Information System (INIS)

Birdsell, K.H.; Campbell, K.; Eggert, K.G.; Travis, B.J.

1989-01-01

This paper presents preliminary transport calculations for radionuclide movement at Yucca Mountain using preliminary data for mineral distributions, retardation parameter distributions, and hypothetical recharge scenarios. These calculations are not performance assessments, but are used to study the effectiveness of the geochemical barriers at the site at mechanistic level. The preliminary calculations presented have many shortcomings and should be viewed only as a demonstration of the modeling methodology. The simulations were run with TRACRN, a finite-difference porous flow and radionuclide transport code developed for the Yucca Mountain Project. Approximately 30,000 finite-difference nodes are used to represent the unsaturated and saturated zones underlying the repository in three dimensions. Sorption ratios for the radionuclides modeled are assumed to be functions of mineralogic assemblages of the underlying rock. These transport calculations present a representative radionuclide cation, 135 Cs and anion, 99 Tc. The effects on transport of many of the processes thought to be active at Yucca Mountain may be examined using this approach. The model provides a method for examining the integration of flow scenarios, transport, and retardation processes as currently understood for the site. It will also form the basis for estimates of the sensitivity of transport calculations to retardation processes. 11 refs., 17 figs., 1 tab

Artificial neural networks application for horizontal and vertical forecasting radionuclides transport

International Nuclear Information System (INIS)

Khil'ko, O.S.; Kovalenko, V.I.; Kundas, S.P.

2010-01-01

Artificial neural networks approach for horizontal and vertical radionuclide transport forecasting was proposed. Runoff factors analysis was considered. Additional artificial neural network structures for physical-chemical properties recognition were used. (authors)

Developing of Watershed Radionuclide Transport Model DHSVM-R as Modification and Extension of Distributed Hydrological and Sediment Dynamics Model DHSVM

Science.gov (United States)

Zheleznyak, M.; Kivva, S.; Onda, Y.; Nanba, K.; Wakiyama, Y.; Konoplev, A.

2015-12-01

The reliable modeling tools for prediction wash - off radionuclides from watersheds are needed as for assessment the consequences of accidental and industrial releases of radionuclides, as for soil erosion studies using the radioactive tracers. The distributed model of radionuclide transport through watershed in exchangeable and nonexchangeable forms in solute and with sediments was developed and validated for small Chernobyl watersheds in 90th within EU SPARTACUS project (van der Perk et al., 1996). New tendency is coupling of radionuclide transport models and the widely validated hydrological distributed models. To develop radionuclide transport model DHSVM-R the open source Distributed Hydrology Soil Vegetation Model -DHSVM http://www.hydro.washington.edu/Lettenmaier/Models/DHSVM was modified and extended. The main changes provided in the hydrological and sediment transport modules of DHSVM are as follows: Morel-Seytoux infiltration model is added; four-directions schematization for the model's cells flows (D4) is replaced by D8 approach; the finite-difference schemes for solution of kinematic wave equations for overland water flow, stream net flow, and sediment transport are replaced by new computationally efficient scheme. New radionuclide transport module, coupled with hydrological and sediment transport modules, continues SPARTACUS's approach, - it describes radionuclide wash-off from watershed and transport via stream network in soluble phase and on suspended sediments. The hydrological module of DHSVM-R was calibrated and validated for the watersheds of Ukrainian Carpathian mountains and for the subwatersheds of Niida river flowing 137Cs in solute and with suspended sediments to Pacific Ocean at 30 km north of the Fukushima Daiichi NPP. The modules of radionuclide and sediment transport were calibrated and validated versus experimental data for USLE experimental plots in Fukushima Prefecture and versus monitoring data collected in Niida watershed. The role

Modelling of radionuclide transport in forests: Review and future perspectives

International Nuclear Information System (INIS)

Shaw, G.; Schell, W.; Linkov, I.

1997-01-01

Ecological modeling is a powerful tool which can be used to synthesize information on the dynamic processes which occur in ecosystems. Models of radionuclide transport in forests were first constructed in the mid-1960's, when the consequences of global fallout from nuclear weapons tests and waste disposal in the environment were of great concern. Such models were developed based on site-specific experimental data and were designed to address local needs. These models had a limited applicability in evaluating distinct ecosystems and deposition scenarios. Given the scarcity of information, the same experimental data sets were often used both for model calibration and validation, an approach which clearly constitutes a methodological error. Even though the carry modeling attempts were far from being faultless, they established a useful conceptual approach in that they tried to capture general processes in ecosystems and thus had a holistic nature. Later, radioecological modeling attempted to reveal ecosystem properties by separating the component parts from the whole system, as an approach to simplification. This method worked well for radionuclide transport in agricultural ecosystems, in which the biogeochemistry of radionuclide cycling is relatively well understood and can be influenced by fertilization. Several models have been successfully developed and applied to human dose evaluation and emergency response to contaminating events in agricultural lands

Distributed models of radionuclide transport on watersheds: development and implementation for the Chernobyl and Fukushima catchments

Energy Technology Data Exchange (ETDEWEB)

Kivva, S.; Zheleznyak, M. [Institute of Environmental Radioactivity, Fukushima University (Japan)

2014-07-01

The distributed hydrological 'rainfall- runoff' models provide possibilities of the physically based simulation of surface and subsurface flow on watersheds based on the GIS processed data. The success of such modeling approaches for the predictions of the runoff and soil erosion provides a basis for the implementation of the distributed radionuclide transport watershed models. Two distributed watershed models of radionuclide transport - RUNTOX and DHSVM-R have been used to simulate the radionuclide transport in the basin of the Dnieper River, Ukraine and watersheds of Prefecture Fukushima. RUNTOX is used for the simulation of radionuclide wash off from the experimental plots and small watersheds, and DHSVM-R is used for medium and large watersheds RUNTOX is two dimensional distributed hydrological model based on the finite-difference solution of the coupled equations the surface flow, subsurface flow, groundwater flow and advection- dispersion equations of the sediments (eroded soil) and radionuclide transport in liquid and solid phases, taking into parameterize the radionuclide exchanges between liquid and solid phases.. This model has been applied to the experimental plots in Ukraine after the Chernobyl accident and experimental plots in the Fukushima Prefecture. The experience of RUNTOX development and application has been used for the extension of the distributed hydrological model DHSVM by the including of the module of the watershed radionuclide transport. The updated model was named by DHSMV-R. The original DHSVM (Distributed Hydrology Soil Vegetation Model) was developed in the University of Washington and Pacific Northwest National Laboratories. DHSVM is a physical distributed hydrology-vegetation model for complex terrain based on the numerical solution of the network of one dimensional equations. The model accounts explicitly for the spatial distribution of land-surface processes, and can be applied over a range of scales, from plot to large

Relative contributions of natural and waste-derived organics to the subsurface transport of radionuclides

International Nuclear Information System (INIS)

Toste, A.P.; Myers, R.B.

1985-06-01

Our laboratory is studying the role of organic compounds in the subsurface transport of radionuclides at shallow-land burial sites of low-level nuclear waste, including a commercial site at Maxey Flats, Kentucky, and an aqueous waste disposal site. At the Maxey Flats site, several radionuclides, notably Pu and 60 Co, appear to exist as anionic, organic complexes. Waste-derived organics, particularly chelating agents such as EDTA, HEDTA and associated degradation products (e.g., ED3A), are abundant in aqueous waste leachates and appear to account for the complexation. EDTA, and probably other waste-derived chelating agents as well, are chelated to the Pu and 60 Co in the leachates, potentially mobilizing these radionuclides. In contrast, at the low-level aqueous waste disposal site, naturally-occurring organics, ranging from low molecular weight (MW) acids to high MW humic acids, account for the bulk of the groundwater's organic content. Certain radionuclides, notably 60 Co, 103 Ru and 125 Sb, are mobile as anionic complexes. These radionuclides are clearly associated with higher MW organics, presumably humic and fulvic acids with nominal MW's > 1000. It is clear, therefore, that naturally-occurring organics may play an important role in radionuclide transport, particularly at nuclear waste burial sites containing little in the way of waste-derived organics

Natural analogue studies of the role of colloids, natural organics and microorganisms on radionuclide transport

International Nuclear Information System (INIS)

McCarthy, J.F.

1994-01-01

Colloids may be important as a geochemical transport mechanism for radionuclides at geological repositories if they are (1) present in the groundwater, (2) stable with respect to both colloidal and chemical stabilities, (3) capable of adsorbing radionuclides, especially if the sorption is irreversible, and (4) mobile in the subsurface. The available evidence from natural analogue and other field studies relevant to these issues is reviewed, as is the potential role of mobile microorganisms (open-quotes biocolloidsclose quotes) on radionuclide migration. Studies have demonstrated that colloids are ubiquitous in groundwater, although colloid concentrations in deep, geochemically stable systems may be too low to affect radionuclide transport. However, even low colloid populations cannot be dismissed as a potential concern because colloids appear to be stable, and many radionuclides that adsorb to colloids are not readily desorbed over long periods. Field studies offer somewhat equivocal evidence concerning colloid mobility and cannot prove or disprove the significance of colloid transport in the far-field environment. Additional research is needed at new sites to properly represent a repository far-field. Performance assessment would benefit from natural analogue studies to examine colloid behavior at sites encompassing a suite of probable groundwater chemistries and that mimic the types of formations selected for radioactive waste repositories

The role of particulates in radionuclide transport

International Nuclear Information System (INIS)

Vilks, P.; Bachinski, D.B.; Vandergraaf, T.T.

1991-01-01

The colloid program at AECL Research is focused on characterizing natural particles in groundwater to evaluate their potential role in radiocolloid formation and to form a database for particle migration studies. The main objective of this program has been the study of colloids (1 to 450 nm) and suspended particles (> 450 nm) in fractured granites and sandstone in various locations in Canada and Switzerland. Groundwater particles were found to consist of clay minerals, micas, quartz, feldspar, iron-silica oxides and organic material. In groundwaters from granite, sandstone and clay-rich rock colloid concentrations were less than 5 mg/L. Some of these groundwaters may contain up to 260 mg/L of suspended particles. However, these particles are not expected to be mobile under the natural flow regimes of deep groundwaters. Provided radiocolloid formation is reversible, it is shown that the colloid concentrations observed in groundwaters from granites will have a negligible effect on radionuclide transport even when making the conservative assumption that these particles travel with the velocity of groundwater. For the case of irreversible radiocolloid formation, an equation is presented to calculate the fraction of total radionuclides in the geosphere which will form radiocolloids. The significance of these radiocolloids will depend upon the total amount of radionuclides released to the geosphere and on particle migration properties. (author)

Radionuclides deposition and fine sediment transport in a forested watershed, central Japan

Science.gov (United States)

Nam, S.; Gomi, T.; Kato, H.; Tesfaye, T.; Onda, Y.

2011-12-01

We investigated radionuclides deposition and fine sediment transport in a 13 ha headwater watershed, Tochigi prefecture, located in 98.94 km north of Tokyo. The study site was within Karasawa experimental forest, Tokyo University of Agriculture and Technology. We conducted fingerprinting approach, based on the activities of fallout radionuclides, including caesium-134 (Cs-134) caesium-137 (Cs-137) and excess lead-210 (Pb-210ex). For indentifying specific sources of fine sediment, we sampled tree, soil on forested floor, soil on logging road surface, stream bed and stream banks. We investigated the radionuclides (i.e., as Cs-134, Cs-137 and Pb-210ex) deposition on tree after accident of nuclear power plants on March 11, 2011. We sampled fruits, leaves, branches, stems, barks on Japanese cedar (Sugi) and Japanese cypress (Hinoki). To analyze the samples, gammaray spectrometry was performed at a laboratory at the University of Tsukuba (Tsukuba City, Japan) using n-type coaxial low-energy HPGe gamma detectors (EGC-200-R and EGC25-195-R of EURYSIS Co., Lingolsheim, France) coupled with a multichannel analyzer. We also collected soil samples under the forest canopy in various soil depths from 2, 5, 10, 20, 30 cm along transect of hillslopes. Samples at forest road were collected road segments crossing on the middle section of monitoring watersheds. Fine sediment transport in the streams were collected at the outlet of 13 ha watersheds using integrated suspended sediment samplers. This study indicates the some portion of radio nuclide potentially remained on the tree surface. Part of the deposited radionuclides attached to soil particles and transported to the streams. Most of the fine sediment can be transported on road surface and/or near stream side (riparian zones).

The influence of the unsaturated zone on the upward transport of radionuclides in soils

International Nuclear Information System (INIS)

Elert, M.; Lindgren, M.

1993-07-01

The transport of radionuclides from the deep soil to the surface soil is an important part of biosphere modelling. In this study the effect of transient hydrological conditions on the upward transport of radionuclides through soils has been studied. The effect of varying soil properties, climate conditions have been considered as well as the effect of a fluctuating groundwater level. It was shown that the soil characteristics influences the radionuclide concentration; an increased hydraulic conductivity leads to increase in the concentration in the root zone. The climate conditions were shown to be of major importance. A dispersion dependent on both velocity and saturation leads to a more effective upward transport of radionuclides to the root zone than if dispersion is assumed to be dependent only on the saturation. The boundary condition used in the case with varying groundwater level may be more realistic than the boundary condition applied for the case with a constant groundwater level. All calculations with varying groundwater level gave lower radionuclide concentration in the root zone. Sorption is redox sensitive for many radionuclides and the redox potential in the soil will be affected by the degree of water saturation. The performed calculations did, however, not result in any significant change in the radionuclide concentration in the root zone due to variation in sorption. A comparison between the results of the two models show that the compartment model in all studied cases predicts a higher annual average radionuclide concentration in the root zone than the numerical model. Annual variation in soil water flow were not included in the compartment model. During the summer the concentration in the root zone may be several times higher than the annual average. This may be important for plant uptake, since this increased concentrations coincides with the plant growing season. The calculations made with the simple compartment model also show that these

LASL models for environmental transport of radionuclides in forests

International Nuclear Information System (INIS)

Gallegos, A.F.; Smith, W.J.; Johnson, L.J.

1978-01-01

The Los Alamos Scientific Laboratory has been developing techniques for evaluating the adequacy of shallow land radioactive disposal sites to contain disposed radionuclides. This report discusses developments in applying a Biological Transport Model to simulate the cycling of plutonium in pinyon-juniper, and ponderosa pine forest ecosystems through serial stage developments using plant growth dynamics created in the model

The transport of natural radionuclides from soil to plants

International Nuclear Information System (INIS)

Bikit, I.; Conkic, Lj.; Slivka, J.; Krmar, M.

1995-01-01

The transport and accumulation processes of Ra-226, U-238, Th-232 and K-40 from soil to plants have been studied. Plant samples with consumable parts grown below surface have been bred in natural conditions on soil with enhanced levels of natural radioactivity (barren soil of the uranium mine Gabrovnica-Kalna). An intensive transport of heavy natural radionuclides from soil to the roots was established. The transfer factors for U-238 and Ra-226 have been much bigger than for Th-232. The most intensive uptake was registered for beet root. (author)

Modeling of U-series Radionuclide Transport Through Soil at Pena Blanca, Chihuahua, Mexico

Science.gov (United States)

Pekar, K. E.; Goodell, P. C.; Walton, J. C.; Anthony, E. Y.; Ren, M.

2007-05-01

The Nopal I uranium deposit is located at Pena Blanca in Chihuahua, Mexico. Mining of high-grade uranium ore occurred in the early 1980s, with the ore stockpiled nearby. The stockpile was mostly cleared in the 1990s; however, some of the high-grade boulders have remained there, creating localized sources of radioactivity for a period of 25-30 years. This provides a unique opportunity to study radionuclide transport, because the study area did not have any uranium contamination predating the stockpile in the 1980s. One high-grade boulder was selected for study based upon its shape, location, and high activity. The presumed drip-line off of the boulder was marked, samples from the boulder surface were taken, and then the boulder was moved several feet away. Soil samples were taken from directly beneath the boulder, around the drip-line, and down slope. Eight of these samples were collected in a vertical profile directly beneath the boulder. Visible flakes of boulder material were removed from the surficial soil samples, because they would have higher concentrations of U-series radionuclides and cause the activities in the soil samples to be excessively high. The vertical sampling profile used 2-inch thicknesses for each sample. The soil samples were packaged into thin plastic containers to minimize the attenuation and to standardize sample geometry, and then they were analyzed by gamma-ray spectroscopy with a Ge(Li) detector for Th-234, Pa-234, U-234, Th-230, Ra-226, Pb-214, Bi-214, and Pb-210. The raw counts were corrected for self-attenuation and normalized using BL-5, a uranium standard from Beaverlodge, Saskatchewan. BL-5 allowed the counts obtained on the Ge(Li) to be referenced to a known concentration or activity, which was then applied to the soil unknowns for a reliable calculation of their concentrations. Gamma ray spectra of five soil samples from the vertical profile exhibit decreasing activities with increasing depth for the selected radionuclides

Box modelling approach for evaluation of influence of ice transport of radionuclides for doses to man

International Nuclear Information System (INIS)

Iospje, M.

2002-01-01

Modelling of the ice transport of radionuclides, which is a unique pathway in the Arctic ocean and adjacent sea areas, is limited by necessity to describe complete processes of incorporation of radioactivity into ice and ice sediment. Freezing / melting processes and transport of 'clean' ice can be described with a good accuracy for relatively short time scale on the basis of the present level of modelling, but detailed description of the sediment entrainment into ice based on the Reynolds equations with attention to coagulation processes is limited by low concentration of particles (grease ice cannot be described) and time scale up to 5 . 10 -2 s (1 . 10 -9 y) what is not available for large time scale and ice masses. Adding the radioactivity incorporation into the ice with following description of transport and fate of radionuclides will lead to further increasing of the complexity of the modelling. Therefore, it is necessary to develop an alternative approach for purposes of radiological assessment on the basis of the box modelling to describe the incorporation of radioactivity into ice and ice sediment, transport of radioactivity by ice and incorporation of radioactivity into sea areas through melding processes. It is shown that the ice transport of radionuclides can be a significant factor for some scenarios and radionuclides. The influence of the ice transport increases with increasing K d values for radionuclides. It is necessary to note that the content and structure of the sediment load in ice vary within wide limits, and therefore, sensitivity and uncertainty analysis can improve the possibility to represent model results satisfactorily. (LN)

Radionuclide transport in fractured media

International Nuclear Information System (INIS)

Williams, M.M.R.

1993-01-01

Until recently, the classical advective-dispersive transport equation was considered to be an adequate model for describing the motion of a solute (e.g. radionuclides) in porous and fractured media. In this model, the dispersion coefficient is either obtained from a microscopic model of the porous medium or by carefully controlled experiments. As a result of such experiments, a large body of data has been accumulated on the dispersivity. Detailed examination of these data has resulted in a curious phenomenon being discovered; namely, that the longitudinal dispersion length is 'scale-dependent'. That is to say the value deduced depends on the 'size' of the experiment, i.e. on the distance over which measurements are made. Several interesting attempts have been made to develop theories which explain this phenomenon, all based on treating the velocity of the water in the porous medium as a spatially random variable, but retaining the advective-dispersive balance equation. In this work we present an entirely new approach to the problem of solute transport in fractured media based upon an analogy with neutron transport. The new method has several advantages over the previous theories and these will be explained below. Results from the new theory are in agreement with experimental trends and do not require any further adjustment to explain the scale-dependent effect

Implementation of the aquatic radionuclide transport models RIVTOX and COASTOX into the RODOS System

International Nuclear Information System (INIS)

Gofman, D.; Lyashenko, G.; Marinets, A.; Mezhueva, I.; Shepeleva, T.; Tkalich, P.; Zheleznyak, M.

1996-01-01

The one -dimensional model of radionuclide transport in a network of river channel RIVTOX and two-dimensional lateral-longitudinal model of radionuclide transport in rivers, reservoirs and shallow lakes COASTOX have been implemented into the hydrological model chain of the decision support system RODOS. The software framework is developed to operate the models and to support their coupling with the other parts of RODOS hydrological model chain. The validation studies were performed for RIVTOX and COASTOX on the base of the data sets from Ukrainian, German and United States rivers

Transport and redistribution of Chernobyl fallout radionuclides by fluvial processes: some preliminary evidence

International Nuclear Information System (INIS)

Walling, D.E.; Bradley, S.B.

1988-01-01

Several measurements of 137 Cs concentrations in suspended sediment transported by the River Severn during the post-Chernobyl period and in recent channel and floodplain deposits along the river emphasise the potential significance of fluvial processes in the transport and concentration of fallout radionuclides. (author)

Radionuclide transport from near-surface repository for radioactive waste - The unsaturated zone approach

Energy Technology Data Exchange (ETDEWEB)

Jakimaviciute-Maseliene, V. [Vilnius University (Lithuania); Mazeika, J. [Nature Research Centre (Lithuania); Motiejunas, S. [Radioactive Waste Management Agency (Lithuania)

2014-07-01

About 100 000 m{sup 3} of solid conditioned Low and Intermediate Level Waste (LILW), generated during operation and decommissioning of the Ignalina nuclear power plant (INPP), are to be disposed of in a near-surface repository (NSR) - a 'hill'-type repository with reinforced concrete vaults and with engineered and natural barriers. The northeastern Lithuania and the environment of the INPP in particular were recognized as the areas most suitable for a near-surface repository (Stabatiske Site). The engineered barriers of the repository consist of concrete cells surrounded by clay-based material of low permeability with about the same isolating capacity in all directions. The clay materials must be effectively compactable so that required hydraulic conductivity is reached. The Lithuanian Triassic clay turned out to be sufficiently rich in smectites and was proposed as main candidate for sealing of the repository. When the concrete vaults are filled, the repository cover will be constructed. The surface of the mound will be planted with grass. In this study a computer code FEFLOW 5.0 was applied for simulating the transport of the most mobile radionuclides ({sup 3}H, {sup 14}C, {sup 59}Ni and {sup 94}Nb) with moisture through an unsaturated vault of the near-surface repository in Stabatiske Site. The HYDRUS-1D analysis was used to assess the radionuclide transport in the repository and to estimate initial activity concentrations of radionuclides transported from the cemented waste matrix. Radionuclide release from the vault in the unsaturated conditions after closure of the repository and consequent contaminant plume transport has been assessed taking into account site-specific natural and engineering conditions and based on a normal evolution scenario. The highest peak radionuclide activity concentrations were estimated applying the FEFLOW code. The highest value of {sup 14}C activity concentration(about 1.3x10{sup 8} Bq/m{sup 3}) at the groundwater table

Radionuclide distribution and transport in terrestrial and aquatic ecosystems. A critical review of data

International Nuclear Information System (INIS)

Coughtrey, P.J.; Jackson, D.; Jones, C.H.; Thorne, M.C.

1984-01-01

These volumes present the results of a study undertaken for the Commission of the European Communities. The aim was to review available data concerning the movement of radionuclides through the environment and to recommend values of parameters for use in environmental transport models. The elements reviewed all have radioactive isotopes which could contribute significantly to the radiological impact of chronic releases of radioactivity from nuclear installations within the countries of the European community, i.e. the major activation and fission products. In dividing these elements between volumes an effort has been made to take account of the method of production of their major radioisotopes, together with their chemical similarities and environmental interactions. This volume covers the radionuclide distribution of americium and curium. The main areas which are covered include the deposition of radionuclides on plants and soils, transport in soils, uptake and translocation in plants via the roots and foliage, metabolism in domestic animals and radionuclide transfers through the main physical and biotic components of the aquatic environment. In reviewing these subject areas, account has been taken not only of the literature relating to specific radionuclides, but also of the literature relating to the stable element of which they are radioisotopes. (Auth.)

The biological transport of radionuclides in grassland and freshwater ecosystems

International Nuclear Information System (INIS)

Rudge, S.A.

1989-12-01

This thesis examines the biological transport of radionuclides through terrestrial and aquatic ecosystems, with particular reference to radiocaesium. The semi-natural grassland habitat was located at Drigg, W. Cumbria, contaminated primarily by radioactive fallout, from several sources over the past decade. Advantage was made of the deposition of radionuclides from the Chernobyl reactor incident, which occurred during the early stages of the investigation. The study examined the distribution of radiocaesium for the major components of the grassland ecosystem, within the soil-plant-invertebrate-small mammal food chain. Data concerning temporal fluctuation of radionuclide transfer factors between food chain components are presented. The final section examines the spatial distribution of radiocaesium in sediment and the freshwater eel (Anguilla anguilla) in a small stream contaminated by radioactive effluent. The relationship between activity levels in eels and the sediments in which they rest and forage was investigated. Factors influencing uptake of radiocaesium in freshwater fish were also examined. (author)

Geosphere transport of radionuclides in safety assessment of spent fuel disposal

Energy Technology Data Exchange (ETDEWEB)

Jussila, P

2000-07-01

The study is associated with a research project of Radiation and Nuclear Safety Authority (STUK) to utilise analytical models in safety assessment for disposal of spent nuclear fuel. Geosphere constitutes a natural barrier for the possible escape of radionuclides from a geological repository of spent nuclear fuel. However, rock contains fractures in which flowing groundwater can transport material. Radionuclide transport in rock is complicated - the flow paths in the geosphere are difficult to characterise and there are various phenomena involved. In mathematical models, critical paths along which radionuclides can reach the biosphere are considered. The worst predictable cases and the effect of the essential parameters can be assessed with the help of such models although they simplify the reality considerably. Some of the main differences between the transport model used and the reality are the mathematical characterisation of the flow route in rock as a smooth and straight fracture and the modelling of the complicated chemical processes causing retardation with the help of a distribution coefficient that does not explain those phenomena. Radionuclide transport models via a heat transfer analogy and analytical solutions of them are derived in the study. The calculations are performed with a created Matlab program for a single nuclide model taking into account 1D advective transport along a fracture, 1D diffusion from the fracture into and within the porous rock matrices surrounding the fracture, retardation within the matrices, and radioactive decay. The results are compared to the results of the same calculation cases obtained by Technical Research Centre of Finland (VTT) and presented in TILA-99 safety assessment report. The model used by VTT is the same but the results have been calculated numerically in different geometry. The differences between the results of the present study and TILA-99 can to a large extent be explained by the different approaches to

Models for transport and fate of carbon, nutrients and radionuclides in the aquatic ecosystem at Oeregrundsgrepen

Energy Technology Data Exchange (ETDEWEB)

Erichsen, Anders Christian; Moehlenberg, Flemming; Closter, Rikke Margrethe; Sandberg, Johannes [DHI, Hoersholm (Denmark)

2010-06-15

The aim of the work was to provide supplementary input to the risk assessment of a planned final nuclear waste repository at Forsmark. The main deliverable was a computed water exchange between basins in the Forsmark marine area for the period 6500 BC to 9000 AD - based on the hydrodynamic modelling - to be used as input to the landscape dose model. In addition and what is described in this report, a second deliverable was development and application of high-resolution models for the marine ecosystem and radionuclide processes. The purpose of this deliverable was to illustrate the spatial and temporal variation in important processes and parameters, while constituting a complement to previous modelling approaches and providing supporting information to discussions of the marine ecosystem, parameters and variation (see Chapter 4 and 6).To this end, a hydrodynamic model of high temporal and spatial resolution was constructed and calibrated for the Forsmark area. An ecosystem model was then developed and coupled to the hydrodynamic model. In turn, a detailed radionuclide model was coupled to the ecosystem model to provide detailed predictions of radionuclide transport and accumulation in the coastal ecosystem. The ecosystem and radionuclide models were developed in the equation solver MIKE ECOLab that links seamless to the MIKE3 FM hydrodynamic model. The 'standard' ECOLab ecosystem model was extended with six biological state variables, perennial macroalgae, benthic herbivors, detritus feeders, planktivorus fish and, benthic predators representing the relict isopod Saduria and cod. In contrast to the ecosystem model, the radionuclide model was developed from scratch but building on the structure of the ecosystem model and using the output (process rates linking state variables) from the ecosystem model as input to the radionuclide model. Both the ecosystem model and the radionuclide model were run for several years (5-8 years) to bring state variables into quasi

Models for transport and fate of carbon, nutrients and radionuclides in the aquatic ecosystem at Oeregrundsgrepen

Energy Technology Data Exchange (ETDEWEB)

Erichsen, Anders Christian; Moehlenberg, Flemming; Closter, Rikke Margrethe; Sandberg, Johannes (DHI, Hoersholm (Denmark))

2010-06-15

The aim of the work was to provide supplementary input to the risk assessment of a planned final nuclear waste repository at Forsmark. The main deliverable was a computed water exchange between basins in the Forsmark marine area for the period 6500 BC to 9000 AD - based on the hydrodynamic modelling - to be used as input to the landscape dose model. In addition and what is described in this report, a second deliverable was development and application of high-resolution models for the marine ecosystem and radionuclide processes. The purpose of this deliverable was to illustrate the spatial and temporal variation in important processes and parameters, while constituting a complement to previous modelling approaches and providing supporting information to discussions of the marine ecosystem, parameters and variation (see Chapter 4 and 6).To this end, a hydrodynamic model of high temporal and spatial resolution was constructed and calibrated for the Forsmark area. An ecosystem model was then developed and coupled to the hydrodynamic model. In turn, a detailed radionuclide model was coupled to the ecosystem model to provide detailed predictions of radionuclide transport and accumulation in the coastal ecosystem. The ecosystem and radionuclide models were developed in the equation solver MIKE ECOLab that links seamless to the MIKE3 FM hydrodynamic model. The 'standard' ECOLab ecosystem model was extended with six biological state variables, perennial macroalgae, benthic herbivors, detritus feeders, planktivorus fish and, benthic predators representing the relict isopod Saduria and cod. In contrast to the ecosystem model, the radionuclide model was developed from scratch but building on the structure of the ecosystem model and using the output (process rates linking state variables) from the ecosystem model as input to the radionuclide model. Both the ecosystem model and the radionuclide model were run for several years (5-8 years) to bring state variables into

Models for transport and fate of carbon, nutrients and radionuclides in the aquatic ecosystem at Oeregrundsgrepen

International Nuclear Information System (INIS)

Erichsen, Anders Christian; Moehlenberg, Flemming; Closter, Rikke Margrethe; Sandberg, Johannes

2010-06-01

The aim of the work was to provide supplementary input to the risk assessment of a planned final nuclear waste repository at Forsmark. The main deliverable was a computed water exchange between basins in the Forsmark marine area for the period 6500 BC to 9000 AD - based on the hydrodynamic modelling - to be used as input to the landscape dose model. In addition and what is described in this report, a second deliverable was development and application of high-resolution models for the marine ecosystem and radionuclide processes. The purpose of this deliverable was to illustrate the spatial and temporal variation in important processes and parameters, while constituting a complement to previous modelling approaches and providing supporting information to discussions of the marine ecosystem, parameters and variation (see Chapter 4 and 6).To this end, a hydrodynamic model of high temporal and spatial resolution was constructed and calibrated for the Forsmark area. An ecosystem model was then developed and coupled to the hydrodynamic model. In turn, a detailed radionuclide model was coupled to the ecosystem model to provide detailed predictions of radionuclide transport and accumulation in the coastal ecosystem. The ecosystem and radionuclide models were developed in the equation solver MIKE ECOLab that links seamless to the MIKE3 FM hydrodynamic model. The 'standard' ECOLab ecosystem model was extended with six biological state variables, perennial macroalgae, benthic herbivors, detritus feeders, planktivorus fish and, benthic predators representing the relict isopod Saduria and cod. In contrast to the ecosystem model, the radionuclide model was developed from scratch but building on the structure of the ecosystem model and using the output (process rates linking state variables) from the ecosystem model as input to the radionuclide model. Both the ecosystem model and the radionuclide model were run for several years (5-8 years) to bring state variables into quasi

Recent developments in the integrated approach toward characterization of radionuclide transport, Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Simmons, A.M.; Canepa, J.A.

1992-01-01

The radionuclide migration program for the Yucca Mountain Site Characterization Project (YMP) includes studies of radionuclide solubility, sorption, diffusion, and transport. The study plans incorporate all possible parameters of investigation; decision-making strategies for prioritizing the parameters and evaluating their significance were developed in conjunction with the study plans. After definition of explicit research goals for each study, YMP evaluated the applicability of existing data and formulated experimental approaches for obtaining additional data. This resulted in development of individual testing strategies that were integrated into an overall strategy for the radionuclide migration program designed to provide input to credible performance assessments. The strategies allow for decision points at various steps of data collection and testing. They provide a streamlined process toward a defensible level of understanding of chemical retardation and transport processes that will be used to predict the mountain's ability to isolate waste. (author)

RIVER-RAD: A computer code for simulating the transport of radionuclides in rivers

International Nuclear Information System (INIS)

Hetrick, D.M.; McDowell-Boyer, L.M.; Sjoreen, A.L.; Thorne, D.J.; Patterson, M.R.

1992-11-01

A screening-level model, RIVER-RAD, has been developed to assess the potential fate of radionuclides released to rivers. The model is simplified in nature and is intended to provide guidance in determining the potential importance of the surface water pathway, relevant transport mechanisms, and key radionuclides in estimating radiological dose to man. The purpose of this report is to provide a description of the model and a user's manual for the FORTRAN computer code

Ecological vectors of radionuclide transport at a solid radioactive waste disposal facility in southeastern Idaho

International Nuclear Information System (INIS)

Arthur, W.J.; Markham, O.D.

1983-01-01

Radioecological research conducted at the Idaho National Engineering Laboratory Subsurface Disposal Area (SDA) has estimated the quantity of radionuclides transported by various ecosystem components and evaluated the impact of subsurface disposal of radioactive waste on biotic species inhabiting the area. Radiation dose rates received by small mammals ranged from 0.4 to 41790 mrad/day. Small mammal soil burrowing was an upward transport mechanism for transuranic radionuclides. Seventy-seven uCi of radioactivity occurred in SDA vegetation annually. None of these ecological vectors contributed appreciable quantities of radioactive contamination to the environment surrounding the SDA

TRING: a computer program for calculating radionuclide transport in groundwater

International Nuclear Information System (INIS)

Maul, P.R.

1984-12-01

The computer program TRING is described which enables the transport of radionuclides in groundwater to be calculated for use in long term radiological assessments using methods described previously. Examples of the areas of application of the program are activity transport in groundwater associated with accidental spillage or leakage of activity, the shutdown of reactors subject to delayed decommissioning, shallow land burial of intermediate level waste and geologic disposal of high level waste. Some examples of the use of the program are given, together with full details to enable users to run the program. (author)

Review of biokinetic and biological transport of transuranic radionuclides in the marine environment

International Nuclear Information System (INIS)

Beasley, T.M.; Cross, F.A.

1980-01-01

Present understanding of the uptake, retention, and loss of transuranic radionuclides by marine biota is limited. Laboratory experiments have demonstrated that for certain species assimilation of plutonium and americium from labeled food is an efficient process and that direct uptake from seawater is important in the bioaccumulation of all transuranic radionuclides studied to date. Organisms appear to play an important role in the vertical transport of these radioelements from the surface layers of the ocean to greater depths

Food web transport of trace metals and radionuclides from the deep sea: a review

International Nuclear Information System (INIS)

Young, J.S.

1979-06-01

This report summarizes aspects of the potential distribution pathways of metals and radionuclides, particularly Co and Ni, through a biological trophic framework after their deposition at 4000 to 5000 meters in the North Atlantic or North Pacific. It discusses (a) the basic, deep-sea trophic structure of eutrophic and oligotrophic regions; (b) the transport pathways of biologically available energy to and from the deep sea, pathways that may act as accumulators and vectors of radionuclide distribution, and (c) distribution routes that have come into question as potential carriers of radionuclides from the deep-sea bed to man

CASCADER: An m-chain gas-phase radionuclide transport and fate model

International Nuclear Information System (INIS)

Cawlfield, D.E.; Been, K.B.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

1993-06-01

Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or diffusion. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. This is volume two to the CASCADER series, titled CASCADR8. It embodies the concepts presented in volume one of this series. To properly understand how the CASCADR8 model works, the reader should read volume one first. This volume presents the input and output file structure for CASCADR8, and a set of realistic scenarios for buried sources of radon gas

Modelling radionuclide transport in the geosphere: a review of the models available

International Nuclear Information System (INIS)

Cacas, M.C.; Cordier, E.; Coudrain-Ribstein, A.; Fargue, D.; Goblet, P.; Jamet, Ph.; Ledoux, E.; Marsily, G. de; Vinsot, A.; Brun, Ch.; Cernes, A.; Jacquier, Ph.; Lewi, J.; Priem, Th.

1990-01-01

Over the last twelve years, several models have been developed to simulate the transport of radionuclides in the environment of a radioactive waste repository: - continuous equivalent porous media flow and transport models using the finite element method in 1, 2 or 3 dimensions and taking into account various coupled mechanisms; - discontinuous stochastic fracture network models in 3 dimensions representing flow, transport, matrix diffusion, heat flow and mechanical stress; - geochemical models representing interactions between transported elements and a solid matrix; - transport process models coupling non dominant phenomena such as thermo-diffusion or thermo-gravitation. This paper reviews the role that each of these models can play in safety analyses. 3 refs [fr

Monitoring and characterization of radionuclide transport in the hydrogeologic system

International Nuclear Information System (INIS)

Phillips, S.J.; Raymond, J.R.

1975-01-01

Historical records pertaining to the 300 North and Wye Burial Grounds at the Hanford Reservation were reviewed as a prerequisite to determining programs for land reclamation. All available historical documents, agency communications, and engineering drawings related to the study areas were located, reviewed, and analyzed. An inventory of recorded location, type, and quantity of radionuclides and associated materials in each burial ground was completed and distributed to cooperating investigators. A geophysical survey of the 300 North Burial Ground was conducted as a basis for detecting the composition, size, distribution, and depth of buried objects and characterizing the sediments in which they are buried. Acoustic, radar, magnetic, and metal detection surveys were completed and their applicability evaluated; drilling techniques and equipment for recovering and characterizing sediments and radioactive contaminated material were developed. Drilling will also determine the amount and dimensional extent of radionuclide migration; sediment-fluid interaction and fluid migration through the unsaturated zone at the 300 North Burial Ground were characterized. A study to determine biological transport of radionuclides at the Wye Burial Ground was also initiated. This study involved a preliminary survey of present flora and fauna inhabiting the Wye Burial Ground site. Plant tissue was chemically and radiochemically analyzed to determine radionuclide migration and possible dose effects and population dynamics of burrowing animals that could potentially be exposed to buried waste materials were investigated

Modelling the transport of radionuclides through the freshwater environment

International Nuclear Information System (INIS)

Hilton, J.; Galvao, J.P.; Foulquier; Pieri, J.; Belli, M.; Vanderbourght, O.

1993-01-01

The main objectives of the project are to identify areas where the present generation of models are breaking down, and to improve the fundamental knowledge in these areas so that more easily transportable (generic) models can be developed. Preliminary studies on the importance of bacteria in the food chain have also been included. Several areas of model limitation have been identified and potential causes have been hypothesized. Steady progress is being made towards the verification of these hypotheses and the ultimate goal of a generic model of radionuclide transport in the aquatic environment. Objectives and results of the nine contributions of the project for the reporting period are discussed. (R.P.) 13 refs., 6 figs., 8 tabs

Radionuclide Transport in Fractured Rock: Numerical Assessment for High Level Waste Repository

Directory of Open Access Journals (Sweden)

Claudia Siqueira da Silveira

2013-01-01

Full Text Available Deep and stable geological formations with low permeability have been considered for high level waste definitive repository. A common problem is the modeling of radionuclide migration in a fractured medium. Initially, we considered a system consisting of a rock matrix with a single planar fracture in water saturated porous rock. Transport in the fracture is assumed to obey an advection-diffusion equation, while molecular diffusion is considered the dominant mechanism of transport in porous matrix. The partial differential equations describing the movement of radionuclides were discretized by finite difference methods, namely, fully explicit, fully implicit, and Crank-Nicolson schemes. The convective term was discretized by the following numerical schemes: backward differences, centered differences, and forward differences. The model was validated using an analytical solution found in the literature. Finally, we carried out a simulation with relevant spent fuel nuclide data with a system consisting of a horizontal fracture and a vertical fracture for assessing the performance of a hypothetical repository inserted into the host rock. We have analysed the bentonite expanded performance at the beginning of fracture, the quantified radionuclide released from a borehole, and an estimated effective dose to an adult, obtained from ingestion of well water during one year.

Geochemical factors affecting radionuclide transport through near and far fields at a Low-Level Waste Disposal Site

International Nuclear Information System (INIS)

Kaplan, D.I.; Seme, R.J.; Piepkho, M.G.

1995-03-01

The concentration of low-level waste (LLW) contaminants in groundwater is determined by the amount of contaminant present in the solid waste, rate of release from the waste and surrounding barriers, and a number of geochemical processes including adsorption, desorption, diffusion, precipitation, and dissolution. To accurately predict radionuclide transport through the subsurface, it is essential that the important geochemical processes affecting radionuclide transport be identified and, perhaps more importantly, accurately quantified and described in a mathematically defensible manner

Sensitivity and uncertainty analysis of the PATHWAY radionuclide transport model

International Nuclear Information System (INIS)

Otis, M.D.

1983-01-01

Procedures were developed for the uncertainty and sensitivity analysis of a dynamic model of radionuclide transport through human food chains. Uncertainty in model predictions was estimated by propagation of parameter uncertainties using a Monte Carlo simulation technique. Sensitivity of model predictions to individual parameters was investigated using the partial correlation coefficient of each parameter with model output. Random values produced for the uncertainty analysis were used in the correlation analysis for sensitivity. These procedures were applied to the PATHWAY model which predicts concentrations of radionuclides in foods grown in Nevada and Utah and exposed to fallout during the period of atmospheric nuclear weapons testing in Nevada. Concentrations and time-integrated concentrations of iodine-131, cesium-136, and cesium-137 in milk and other foods were investigated. 9 figs., 13 tabs

Radionuclide transport in a single fissure

International Nuclear Information System (INIS)

Eriksen, T.E.

1984-01-01

Radionuclide migration has been studied in natural fissures running parallel to the axes of granitic drill cores. A short pulse of radionuclide solution was injected at one end of the fissure and the temporal change in radionuclide concentration of the eluate measured. At the end of each experiment the fissure was opened and the radionuclide distribution on the fissure surfaces measured. The retardation of 241 Am(III) at pH 8.2 as well as the variation in 235 Np(V) retardation with pH are found to be in good agreement with K d-values obtained in batch experiments. The reduction of (TcO - 4 ) to Tc(IV) leads as expected to increasing retardation.(author)

Assessment of hydrologic transport of radionuclides from the Rulison Underground Nuclear Test Site, Colorado

International Nuclear Information System (INIS)

Earman, S.; Chapman, J.; Andricevic, R.

1996-09-01

The U.S. Department of Energy (DOE) is operating an environmental restoration program to characterize, remediate, and close non-Nevada Test Site locations that were used for nuclear testing. Evaluation of radionuclide transport by groundwater from these sites is an important part of the preliminary risk analysis. These evaluations are undertaken to allow prioritization of the test areas in terms of risk, provide a quantitative basis for discussions with regulators and the public about future work at the sites, and provide a framework for assessing data needs to be filled by site characterization. The Rulison site in west-central Colorado was the location of an underground detonation of a 40-kiloton nuclear device in 1969. The test took place 2,568 m below ground surface in the Mesaverde Formation. Though located below the regional water table, none of the bedrock formations at the site yielded water during hydraulic tests, indicating extremely low permeability conditions. The scenario evaluated was the migration of radionuclides from the blast-created cavity through the Mesaverde Formation. Transport calculations were performed using the solute flux method, with input based on the limited data available for the site. Model results suggest that radionuclides from the test are contained entirely within the area currently administered by DOE. The transport calculations are most sensitive to changes in the mean groundwater velocity and the correlation scale of hydraulic conductivity, with transport of strontium and cesium also sensitive to the sorption coefficient

Materials to be used for radionuclide transport experiments (milestones SPL3A1M4)

International Nuclear Information System (INIS)

Viani, B.

1998-02-01

Experiments to determine the effect of canister corrosion products on the transport of radionuclides will be undertaken using the FE(III) oxides goethite and hematite as proxies for the expected corrosion envelope that will form as a result of alteration of the corrosion allowance overpack prior to the breaching of the waste container. Samples of ESF invert concrete that have been crushed, or left intact but fractured, and that have been subjected to hydrothermal alteration will be used to determine the effect of cementitious materials on transport of radionuclides. A mixture of CaCO 3 , Si0 2 , and aggregate will be used as a proxy for completely carbonated concrete

Numerical solution of the radionuclide transport equation

International Nuclear Information System (INIS)

Hadermann, J.; Roesel, F.

1983-11-01

A numerical solution of the one-dimensional geospheric radionuclide chain transport equation based on the pseudospectral method is developed. The advantages of this approach are flexibility in incorporating space and time dependent migration parameters, arbitrary boundary conditions and solute rock interactions as well as efficiency and reliability. As an application the authors investigate the impact of non-linear sorption isotherms on migration in crystalline rock. It is shown that non-linear sorption, in the present case a Freundlich isotherm, may reduce concentration at the geosphere outlet by orders of magnitude provided the migration time is comparable or larger than the half-life of the nuclide in question. The importance of fixing dispersivity within the continuum approach is stressed. (Auth.)

Organic material in clay-based buffer materials and its potential impact on radionuclide transport

International Nuclear Information System (INIS)

Vilks, P.; Goulard, M.; Stroes-Gascoyne, S.; Haveman, S.A.; Bachinski, D.B.; Hamon, C.J.; Comba, R.

1997-03-01

AECL has submitted an Environmental Impact Statement (EIS) to evaluate the concept of nuclear fuel disposal at depth in crystalline rock of the Canadian Shield. In this disposal concept used fuel would be emplaced in corrosion-resistant containers which would be surrounded by clay-based buffer and backfill materials. Once groundwater is able to penetrate the buffer and corrosion-resistant container, radionuclides could be transported from the waste form to the surrounding geosphere, and eventually to the biosphere. The release of radionuclides from the waste form and their subsequent transport would be determined by the geochemistry of the disposal vault and surrounding geosphere. Organic substances affect the geochemistry of radionuclides through complexation reactions that increase solubility and alter mobility, by affecting the redox of certain radionuclides and by providing food for microbes. The purpose of this study was to determine whether the buffer and backfill materials proposed for use in a disposal vault contain organics that could be leached by groundwater in large enough quantities to complex with radionuclides and affect their mobility within the disposal vault and surrounding geosphere. Buffer material, made from a mixture of 50 wt.% Avonlea sodium bentonite and 50 wt.% silica sand, was extracted with deionized water to determine the release of dissolved organic carbon, humic acid and fulvic acid. The effect of radiation and heat from the used fuel was simulated by treating samples of buffer before leaching to various amounts of heat (60 deg C and 90 deg C) for periods of 2, 4 and 6 weeks, and to ionizing radiation with doses of 25 kGy and 50 kGy. Humic substances were isolated from the leachates to determine the concentrations of humic and fulvic acids and to determine their functional group content by acid-base titrations. The results showed that groundwater would leach significant amounts of organics that would complex with radionuclides such as

A regional sediment transport modeling for fluvial influx and redistribution of suspended radionuclide in the Fukushima coast

International Nuclear Information System (INIS)

Uchiyama, Yusuke; Yamanishi, Takafumi; Tsumune, Daisuke; Miyazawa, Yasumasa

2014-01-01

Fluvial discharge from the rivers is viewed as a missing piece for the inventory of the radionuclides in the ocean during the accident at the Fukushima Daiichi Nuclear Power Plant. The land-derived input introduces a time lag behind the direct release through hydrological process because these radionuclides mostly attach to suspended particles (sediments) that are transported quite differently to the dissolved matter in the ocean. We therefore develop a regional sediment transport model consisting of a multi-class non-cohesive sediment transport module, a wave-enhanced bed boundary layer model and a stratigraphy model proposed by Blaas et al. (2007) based on ROMS. (author)

Radionuclide transport modelling for a buried near surface low level radioactive waste

International Nuclear Information System (INIS)

Terzi, R.

2004-01-01

The disposal of radioactive waste, which is the last step of any radioactive waste management policy, has not yet been developed in Turkey. The existing legislation states only the discharge limits for the radioactive wastes to be discharged to the environment. The objective of this modelling study is to assist in safety assessment and selecting disposal site for gradually increasing non-nuclear radioactive wastes. This mathematical model has been developed for the environmental radiological assessment of near surface disposal sites for the low and intermediate level radioactive wastes. The model comprised of three main components: source term, geosphere transport and radiological assessment. Radiation dose for the babies (1 years age) and adults (≥17 years age) have been computed for the radionuclides Cesium 137 (Cs-137) and Strontium 90 (Sr-90), having the activity of 1.10 12 Becquerel(Bq), in radioactive waste through transport of radionuclide in liquid phase with the various pathways. The model consisted of first order ordinary differential equations was coded as a TCODE file in MATLAB program. The radiation dose to man for the realist case and low probability case have been calculated by using Runge-Kutta solution method in MATLAB programme for radionuclide transport from repository to soil layer and then to the ground water(saturated zone) through drinking water directly and consuming agricultural and animal products pathways in one year period. Also, the fatal cancer risk assessment has been made by taking into account the annual dose received by people. Various dose values for both radionuclides have been found which depended on distribution coefficient, retardation factor and dose conversion factors. The most important critical parameters on radiological safety assessment are the distribution coefficient in soil layer, seepage velocity in unsaturated zone and thickness of the unsaturated zone (soil zone). The highest radiation dose and average dose to

Multicomponent mass transport model: a model for simulating migration of radionuclides in ground water

International Nuclear Information System (INIS)

Washburn, J.F.; Kaszeta, F.E.; Simmons, C.S.; Cole, C.R.

1980-07-01

This report presents the results of the development of a one-dimensional radionuclide transport code, MMT2D (Multicomponent Mass Transport), for the AEGIS Program. Multicomponent Mass Transport is a numerical solution technique that uses the discrete-parcel-random-wald (DPRW) method to directly simulate the migration of radionuclides. MMT1D accounts for: convection;dispersion; sorption-desorption; first-order radioactive decay; and n-membered radioactive decay chains. Comparisons between MMT1D and an analytical solution for a similar problem show that: MMT1D agrees very closely with the analytical solution; MMT1D has no cumulative numerical dispersion like that associated with solution techniques such as finite differences and finite elements; for current AEGIS applications, relatively few parcels are required to produce adequate results; and the power of MMT1D is the flexibility of the code in being able to handle complex problems for which analytical solution cannot be obtained. Multicomponent Mass Transport (MMT1D) codes were developed at Pacific Northwest Laboratory to predict the movement of radiocontaminants in the saturated and unsaturated sediments of the Hanford Site. All MMT models require ground-water flow patterns that have been previously generated by a hydrologic model. This report documents the computer code and operating procedures of a third generation of the MMT series: the MMT differs from previous versions by simulating the mass transport processes in systems with radionuclide decay chains. Although MMT is a one-dimensional code, the user is referred to the documentation of the theoretical and numerical procedures of the three-dimensional MMT-DPRW code for discussion of expediency, verification, and error-sensitivity analysis

Evaluation of conceptual, mathematical and physical-and-chemical models for describing subsurface radionuclide transport at the Lake Karachai Waste Disposal Site

International Nuclear Information System (INIS)

Rumynin, V.G.; Mironenko, V.A.; Sindalovsky, L.N.; Boronina, A.V.; Konosavsky, P.K.; Pozdniakov, S.P.

1998-01-01

The goal of this work was to develop the methodology and to improve understanding of subsurface radionuclide transport for application to the Lake Karachai Site and to identify the influence of the processes and interactions involved into transport and fate of the radionuclides. The report is focused on two sets of problems, which have to do both with, hydrodynamic and hydrogeochemical aspects of the contaminant transport

Transport of a Two-Member Decay Chain of Radionuclides Through a Discrete Fracture in a Porous Rock Matrix in the Presence of Colloids

International Nuclear Information System (INIS)

Tien, N.-C.; Li Shihhai

2002-01-01

Many physical and chemical processes dominate the transport of radionuclides in groundwater. Among these processes, the decay chain process of radionuclides was frequently disregarded in previous research. However, the daughter products may travel much farther than their parents along the fracture. Therefore, some models neglecting the effect of the decay chain may underestimate the transport radionuclide concentration in geological media. The transport of radionuclides in groundwater is also controlled by colloidal particles. The radionuclides may be enhanced or retarded by the colloids, according to the mobility of these colloidal particles. This work describes a novel model of the transport of a two-member decay chain of radionuclides through a discrete fracture in a porous rock matrix in the presence of colloids. The model addresses the following processes: (a) advective transport in the fracture, (b) mechanical dispersion and molecular diffusion along the fracture, (c) molecular diffusion from the fracture to the rock matrix, (d) adsorption onto the fracture wall, (e) adsorption in the rock matrix, and (f) radioactive decay. Furthermore, colloids are assumed to be excluded from the matrix pores because of their size. A fully developed concentration profile system with nonreactive colloids is used to understand the effect of colloidal sizes by using hydrodynamic chromatography. The external forces acting on the colloid surface, such as the inertial, the van der Waals attractive force, the double layer force, and the gravitational force are accounted for. The parameters, the average velocity of the colloid, the dispersion coefficient of the colloid, and the distribution coefficient of radionuclides with colloids are modified according to the colloidal size. The transport equations for the parent radionuclides are solved analytically using the Laplace transformation and inversion method. However, for the transformed solution of the daughter products along the

Modelling of natural organic matter-linked radionuclide transport in Boom clay

International Nuclear Information System (INIS)

Govaerts, J.; Maes, N.

2012-01-01

Document available in extended abstract form only. In the framework of the Belgian research program on long term management of high-level and/or long-lived radioactive wastes coordinated by ONDRAF/NIRAS, Boom Clay is investigated for its potential to host a deep geological disposal repository. In order to demonstrate the suitability of the Boom Clay as a host rock, the mobility of critical radionuclides in this clay layer has been the subject of research during many years. As actinides, lanthanides and transition metals are known to form strong complexes with organic substances, the influence of the Natural Organic Matter (NOM) present in Boom Clay on the mobility of these critical radionuclides is of crucial importance. Interaction of radionuclides with OM present in Boom Clay could on the one hand retard the migration due to complexation/colloid interaction with the immobile OM, and on the other hand the mobility and solubility of the radionuclide can be enhanced by the formation of complexes/colloids with the mobile OM. The conceptual understanding (and its numerical modelling) of the kinetic stability and transport of these complexes/colloids is therefore regarded as highly important for the the long-term safety assesment of the geological disposal. This can be broken down into two subproblems: 1. Describing the transport behaviour of mobile OM in Boom Clay; 2. Describing the interaction of RN with mobile OM and the transport behaviour of the resulting complexes in Boom Clay. The first part of this paper revolves around the first subproblem, where a robust model for the description of the migration behaviour of Natural Organic Matter (NOM) is derived based on data from column migration experiments using 14 C-labelled NOM Tracer solution, obtained in the framework of the EC TRANCOM-II project. Clay plugs of different lengths and different Darcy velocities were used. Inverse modelling with the MATLAB and COMSOL numerical code was done in order to identify the

Marine biogeochemistry of radionuclides

International Nuclear Information System (INIS)

Fowler, S.W.

1997-01-01

Radionuclides entering the ocean from runoff, fallout, or deliberate release rapidly become involved in marine biogeochemical cycles. Sources, sinks and transport of radionuclides and analogue elements are discussed with emphasis placed on how these elements interact with marine organisms. Water, food and sediments are the source terms from which marine biota acquire radionuclides. Uptake from water occurs by surface adsorption, absorption across body surfaces, or a combination of both. Radionuclides ingested with food are either assimilated into tissue or excreted. The relative importance of the food and water pathway in uptake varies with the radionuclide and the conditions under which exposure occurs. Evidence suggests that, compared to the water and food pathways, bioavailability of sediment-bound radionuclides is low. Bioaccumulation processes are controlled by many environmental and intrinsic factors including exposure time, physical-chemical form of the radionuclide, salinity, temperature, competitive effects with other elements, organism size, physiology, life cycle and feeding habits. Once accumulated, radionuclides are transported actively by vertical and horizontal movements of organisms and passively by release of biogenic products, e.g., soluble excreta, feces, molts and eggs. Through feeding activities, particles containing radionuclides are ''packaged'' into larger aggregates which are redistributed upon release. Most radionuclides are not irreversibly bound to such particles but are remineralized as they sink and/or decompose. In the pelagic zones, sinking aggregates can further scavenge particle-reactive elements thus removing them from the surface layers and transporting them to depth. Evidence from both radiotracer experiments and in situ sediment trap studies is presented which illustrates the importance of biological scavenging in controlling the distribution of radionuclides in the water column. (author)

Organic matter linked radionuclide transport in Boom clay - Phenomenological understanding and abstraction to PA

International Nuclear Information System (INIS)

Maes, N.; Bruggeman, C.; Liu, D.J.; Salah, S.; Van Laer, L.; Wang, L.; Weetjens, E.; Govaerts, J.; Marivoet, J.; Brassinnes, S.

2012-01-01

Document available in extended abstract form only. In the frame of the Belgian research program on long term management of high-level and/or long-lived radioactive wastes coordinated by ONDRAF/NIRAS, plastic clays (i.e., Boom Clay and Ypresian clays) are investigated for their potential to host a deep geological disposal repository for radioactive waste because of, among others, their ability to significantly retard radionuclide releases to the biosphere. The Boom Clay is characterised by the presence of a relatively high amount of dissolved organic matter (DOM, humic substances) which show a strong interaction with a suite of radionuclides (RN) like lanthanides, actinides and transition metals. This interaction with DOM leads in general to an increased mobility of the radionuclide as the OM can act as a colloidal carrier for the radionuclide. Therefore, the quantification and the understanding of the underlying processes are needed for the demonstration of confidence in the host formation to act as a suitable barrier. However, this is not an easy task, given the multitude of processes involved: complexation/colloid formation, sorption, kinetics, filtration, -. In this presentation, we will provide an overview of the research work that leads to a straightforward reactive transport model capturing fairly well the experimental observations. The model can be considered as an intermediate model providing a good basis for further safety abstraction on the one hand and the way to a more detailed phenomenological understanding on the other hand. The research is focussed on the underlying processes that govern speciation, sorption and transport. These underlying processes are investigated in a bottom-up approach, from simple systems to more complex systems. Interpretation is done using thermodynamic based models. Whereas the contribution of Bruggeman et al. focusses mainly on (batch) sorption studies (of trivalent RN), this presentation will provide more details on the

Summary of the data which is used for radionuclide transport analysis in the groundwater

International Nuclear Information System (INIS)

Koga, Osamu; Nagara, Shuichi; Matsumura, Toshihiro; Takeuchi, Akira; Takeda, Shinji; Sato, Kazuhiko; Tokizawa, Takayuki

2004-03-01

To analyze high precision in groundwater flow and radionuclide transport around Yotsugi open-pit mining place site and around Yotsugi mill tailing yard, besides the topic in past analysis is extracted, following it did examination of the corresponding method and arrangement of physical properties value. It investigated concerning the 3-dimensional flow and transport analysis code which can handle the chain-radionuclide selected. The range of the analytical area examined that become the object of groundwater flow and transport analysis, the wide area, Yotsugi open-pit mining place site and Yotsugi mill tailing yard selected the analytical model area, concerning the range which is surrounded with the divide. Receiving the influence of the alteration zone and the crush zone concerning the coefficient of permeability of the granite, it re-appraised excluding the value which is supposed that water permeability is high. The weathered granite from the lithofacies divided in the high weathered granite and the low weathered granite. As for the geometrical mean of coefficient of permeability of the former 10 -6 m/s order, the later 10 -8 m/s order, there is a difference of 2 orders in both. In addition, the data which is obtained to this year concerning physical properties value for analysis, groundwater level, precipitation and radionuclide density etc. rearranged and data set drew up. (author)

Tracing Fukushima Radionuclides in the Northern Hemisphere -An Overview

Science.gov (United States)

Thakur, Punam; Ballard, Sally; Nelson, Roger

2013-04-01

A massive 9.0 earthquake and ensuing tsunami struck the northern coast of the Honshu-island, Japan on March 11, 2011 and severely damaged the electric system of the Fukushima- Daiichi Nuclear Power Plant (NPP). The structural damage to the plant disabled the reactor's cooling systems. Subsequent fires, a hydrogen explosion and possible partial core meltdowns released radioactive fission products into the atmosphere. The atmospheric release from the crippled Fukushima NPP started on March 12, 2011 with a maximum release phase from March 14 to 17. The radioactivity released was dominated by volatile fission products including isotopes of the noble gases xenon (Xe-133) and krypton (Kr-85); iodine (I-131,I-132); cesium (Cs-134,Cs-136,Cs-137); and tellurium (Te-132). The non-volatile radionuclides such as isotopes of strontium and plutonium are believed to have remained largely inside the reactor, although there is evidence of plutonium release into the environment. Global air monitoring across the northern hemisphere was increased following the first reports of atmospheric releases. According to the source term, declared by the Nuclear and Industrial Safety Agency (NISA) of Japan), approximately 160 PBq (1 PBq (Peta Becquerel = 10^15 Bq)) of I-131 and 15 PBq of Cs-137 (or 770 PBq "iodine-131 equivalent"), were released into the atmosphere. The 770 PBq figure is about 15% of the Chernobyl release of 5200 PBq of "iodine-131 equivalent". For the assessment of contamination after the accident and to track the transport time of the contaminated air mass released from the Fukushima NPP across the globe, several model calculations were performed by various research groups. All model calculations suggested long-range transport of radionuclides from the damaged Fukushima NPP towards the North American Continent to Europe and to Central Asia. As a result, an elevated level of Fukushima radionuclides were detected in air, rain, milk, and vegetation samples across the northern

Modified finite element transport model, FETRA, for sediment and radionuclide migration in open coastal waters

International Nuclear Information System (INIS)

Onishi, Y.; Arnold, E.M.; Mayer, D.W.

1979-08-01

The finite element model, FETRA, simulates transport of sediment and radionuclides (and other contaminants, such as heavy metals, pesticides, and other toxic substances) in surface water bodies. The model is an unsteady, two-dimensional (longitudinal and lateral) model which consists of the following three submodels coupled to include sediment-contaminant interactions: (1) sediment transport submodel, (2) dissolved contaminant transport submodel, and (3) particulate contaminant (contaminant adsorbed by sediment) transport submodel. Under the current phase of the study, FETRA was modified to include sediment-wave interaction in order to extend the applicability of the model to coastal zones and large lakes (e.g., the Great Lakes) where wave actions can be one of the dominant mechanisms to transport sediment and toxic contaminant. FETRA was further modified to handle both linear and quadratic approximations to velocity and depth distributions in order to be compatible with various finite element hydrodynamic models (e.g., RMA II and CAFE) which supply hydrodynamic input data to FETRA. The next step is to apply FETRA to coastal zones to simulate transport of sediment and radionuclides with their interactions in order to test and verify the model under marine and large lacustrine environments

Database for radionuclide transport in the biosphere

International Nuclear Information System (INIS)

Jiskra, J.

1985-01-01

The biosphere model is the final link in the chain of radionuclide transport models, used for radiation dose calculations from high level waste repositories. This report presents the data needed for biosphere calculations and discusses them where necessary. The first part is dedicated to the nuclide specific parameters like distribution coefficients (water - soil), concentration ratios (soil - plant) and distribution factors (for milk, meat etc.) which are reported in the literature. The second part contains the choice of regions, their division into compartments and the discussion of nutritional habits for man and animals. At the end a theoretical population for each region is estimated based on the consumption rates and on the yield of agricultural products, assuming an autonomous nutrition. (Auth.)

A review on studies of the transport and the form of radionuclides in the fluvial environment

Energy Technology Data Exchange (ETDEWEB)

Matsunaga, Takeshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2001-06-01

The Japan Atomic Energy Research Institute has conducted studies with an aim to contribute to understanding the long-term behavior of atmospherically-derived radionuclides deposited on the ground. The present report reviews a series of studies among them which have especially dealt with the behavior of those radionuclides in a fluvial environment. The studies cited here include investigations of 1) the evaluation of the transport rate of the atmospherically-derived radionuclides from the ground via a river to the downstream areas where the affected water is consumed; 2) the physico-chemical form of the radionuclides in the fluvial environment. An investigation in the Kuji river watershed with {sup 137}Cs, {sup 210}Pb and {sup 7}Be has validated i) the importance of suspended particulate materials in the fluvial discharge of those radionuclides, and ii) a methodology to estimate the discharge of those radionuclides based on the regression analysis with the river water flow rate. From a viewpoint of their distribution between water and suspended particles, the form of radionuclides released by the Chernobyl accident in rivers and lakes in the vicinity of the Chernobyl Nuclear Power Plant were analyzed. As a result, a general reasonability and some cautions were suggested when commonly reported distribution ratios obtained in the laboratory and the different environment are applied to describe the partitioning of the radionuclides in specific natural environmental conditions. This experimental investigation in Chernobyl also revealed the role of natural dissolved organics in affecting the dissolution and transport of {sup 239,240}Pu, {sup 241}Am through complexation to form soluble species. Further, a chemical equilibrium model was applied to describe this complexation. The similar model was also applied for the behavior of iron and manganese (hydr)oxides in river recharged aquifers which can bear riverborne radionuclides and can influence their migration. The

A review on studies of the transport and the form of radionuclides in the fluvial environment

International Nuclear Information System (INIS)

Matsunaga, Takeshi

2001-06-01

The Japan Atomic Energy Research Institute has conducted studies with an aim to contribute to understanding the long-term behavior of atmospherically-derived radionuclides deposited on the ground. The present report reviews a series of studies among them which have especially dealt with the behavior of those radionuclides in a fluvial environment. The studies cited here include investigations of 1) the evaluation of the transport rate of the atmospherically-derived radionuclides from the ground via a river to the downstream areas where the affected water is consumed; 2) the physico-chemical form of the radionuclides in the fluvial environment. An investigation in the Kuji river watershed with 137 Cs, 210 Pb and 7 Be has validated i) the importance of suspended particulate materials in the fluvial discharge of those radionuclides, and ii) a methodology to estimate the discharge of those radionuclides based on the regression analysis with the river water flow rate. From a viewpoint of their distribution between water and suspended particles, the form of radionuclides released by the Chernobyl accident in rivers and lakes in the vicinity of the Chernobyl Nuclear Power Plant were analyzed. As a result, a general reasonability and some cautions were suggested when commonly reported distribution ratios obtained in the laboratory and the different environment are applied to describe the partitioning of the radionuclides in specific natural environmental conditions. This experimental investigation in Chernobyl also revealed the role of natural dissolved organics in affecting the dissolution and transport of 239,240 Pu, 241 Am through complexation to form soluble species. Further, a chemical equilibrium model was applied to describe this complexation. The similar model was also applied for the behavior of iron and manganese (hydr)oxides in river recharged aquifers which can bear riverborne radionuclides and can influence their migration. The obtained findings and the

The role of organic complexants and microparticulates in the facilitated transport of radionuclides

International Nuclear Information System (INIS)

Schilk, A.J.; Robertson, D.E.; Abel, K.H.; Thomas, C.W.

1996-12-01

This progress report describes the results of ongoing radiological and geochemical investigations of the mechanisms of radionuclide transport in groundwater at two low-level waste (LLW) disposal sites within the waste management area of the Chalk River Laboratories (CRL), Ontario, Canada. These sites, the Chemical Pit liquid disposal facility and the Waste Management Area C solid LLW disposal site, have provided valuable 30- to 40-year-old field locations for characterizing the migration of radionuclides and evaluating a number of recent site performance objectives for LLW disposal facilities. This information will aid the NRC and other federal, state, and local regulators, as well as LLW disposal site developers and waste generators, in maximizing the effectiveness of existing or projected LLW disposal facilities for isolating radionuclides from the general public and thereby improving the health and safety aspects of LLW disposal

Study on radionuclides transport from natural evaporating ponds to the atmosphere

International Nuclear Information System (INIS)

Liu Keqiang; Zou Changgui

1997-08-01

The results of simulated experiments, field monitoring and radiation health risk evaluation of radionuclides transport to the atmosphere from the natural evaporating ponds of a certain nuclear factory, and the estimating method of releasing source strength are presented. The estimated results of radiation health risk show that the maximum individual annual risk is 6.5 x 10 -9 and the total collective annual risk within a radius of 20 km is 3.2 x 10 -5 person, which are caused by operation of the evaporating ponds. It should be pointed out that the above estimated results only refer to one operating year (1990). If the cumulative effect of radionuclides deposition in ground is considered, the risk will increase a little with time until the dynamic balance is achieved. (5 ref., 8 tabs.)

Wind Transport of Radionuclide- Bearing Dust, Peña Blanca, Chihuahua, Mexico

Science.gov (United States)

Velarde, R.; Goodell, P. C.; Gill, T. E.; Arimoto, R.

2007-05-01

This investigation evaluates radionuclide fractionation during wind erosion of high-grade uranium ore storage piles at Peña Blanca (50km north of Chihuahua City), Chihuahua, Mexico. The aridity of the local environment promotes dust resuspension by high winds. Although active operations ceased in 1983, the Peña Blanca mining district is one of Mexico`s most important uranium ore reserves. The study site contains piles of high grade ore, left loose on the surface, and separated by the specific deposits from which they were derived (Margaritas, Nopal I, and Puerto I). Similar locations do not exist in the United States, since uranium mining sites in the USA have been reclaimed. The Peña Blanca site serves as an analog for the Yucca Mountain project. Dust deposition is collected at Peña Blanca with BSNE sediment catchers (Fryrear, 1986) and marble dust traps (Reheis, 1999). These devices capture windblown sediment; subsequently, the sample data will help quantify potentially radioactive short term field sediment loss from the repository surface and determine sediment flux. Aerosols and surface materials will be analyzed and radioactivity levels established utilizing techniques such as gamma spectroscopy. As a result, we will be able to estimate how much radionuclide contaminated dust is being transported or attached geochemically to fine grain soils or minerals (e.g., clays or iron oxides). The high-grade uranium-bearing material is at secular equilibrium, thus the entire decay series is present. Of resulting interest is not only the aeolian transport of uranium, but also of the other daughter products. These studies will improve our understanding of geochemical cycling of radionuclides with respect to sources, transport, and deposition. The results may also have important implications for the geosciences and homeland security, and potential applications to public health. Funding for this project is provided in part via a NSF grant to Arimoto.

Colloid-facilitated radionuclide transport in the fractured rock: effects of decay chain and limited matrix diffusion

International Nuclear Information System (INIS)

Park, J. B.; Park, J. W.; Lee, E. Y.; Kim, C. R.

2002-01-01

Colloid-facilitated radionuclide transport in the fractured rock is studies by considering radioactive decay chain and limited matrix diffusion into surrounding porous media. Semi-analytical solution in the Laplace domain is obtained from the mass balance equation of radionuclides and colloid particles. Numerical inversion of the Laplace solution is used to get the concentration profiles both in a fracture and in rock matrix. There issues are analyzed for the radionuclide concentration in a fracture by 1) formation constant of pseudo-colloid, 2) filtration coefficient of radio-colloid and 3) effective diffusion depth into the surrounding porous rock media

Obtaining and testing of the arbuscular mycorrhizal fungies inocula for the modification of radionuclides transport into the plants

International Nuclear Information System (INIS)

Kryipka, A.V.; Sorochins'kij, B.V.

2003-01-01

Spores of the arbuscular mycorrhizal (AM) fungies have been isolaten from the plants collected at the Chernobyl zone. Selection of the plants were done due to their high radionuclides' accumulation ability and AM colonization level as well. These spores were used to start the inocula production for the plant treatment aimed to affect radionuclides transport. Spores identification was done based on their morphological and molecular features. Three different AM inocula with high potential to modify 90 Sr and 137 Cs transport at the phytoremediation experiments were obtained

Modeling Radionuclide Decay Chain Migration Using HYDROGEOCHEM

Science.gov (United States)

Lin, T. C.; Tsai, C. H.; Lai, K. H.; Chen, J. S.

2014-12-01

Nuclear technology has been employed for energy production for several decades. Although people receive many benefits from nuclear energy, there are inevitably environmental pollutions as well as human health threats posed by the radioactive materials releases from nuclear waste disposed in geological repositories or accidental releases of radionuclides from nuclear facilities. Theoretical studies have been undertaken to understand the transport of radionuclides in subsurface environments because that the radionuclide transport in groundwater is one of the main pathway in exposure scenarios for the intake of radionuclides. The radionuclide transport in groundwater can be predicted using analytical solution as well as numerical models. In this study, we simulate the transport of the radionuclide decay chain using HYDROGEOCHEM. The simulated results are verified against the analytical solution available in the literature. Excellent agreements between the numerical simulation and the analytical are observed for a wide spectrum of concentration. HYDROGECHEM is a useful tool assessing the ecological and environmental impact of the accidental radionuclide releases such as the Fukushima nuclear disaster where multiple radionuclides leaked through the reactor, subsequently contaminating the local groundwater and ocean seawater in the vicinity of the nuclear plant.

Fukushima Daiichi-Derived Radionuclides in the Ocean: Transport, Fate, and Impacts.

Science.gov (United States)

Buesseler, Ken; Dai, Minhan; Aoyama, Michio; Benitez-Nelson, Claudia; Charmasson, Sabine; Higley, Kathryn; Maderich, Vladimir; Masqué, Pere; Morris, Paul J; Oughton, Deborah; Smith, John N

2017-01-03

The events that followed the Tohoku earthquake and tsunami on March 11, 2011, included the loss of power and overheating at the Fukushima Daiichi nuclear power plants, which led to extensive releases of radioactive gases, volatiles, and liquids, particularly to the coastal ocean. The fate of these radionuclides depends in large part on their oceanic geochemistry, physical processes, and biological uptake. Whereas radioactivity on land can be resampled and its distribution mapped, releases to the marine environment are harder to characterize owing to variability in ocean currents and the general challenges of sampling at sea. Five years later, it is appropriate to review what happened in terms of the sources, transport, and fate of these radionuclides in the ocean. In addition to the oceanic behavior of these contaminants, this review considers the potential health effects and societal impacts.

Assessment of hydrologic transport of radionuclides from the Gasbuggy underground nuclear test site, New Mexico

International Nuclear Information System (INIS)

Earman, S.; Chapman, J.; Andricevic, R.

1996-09-01

The U.S. Department of Energy (DOE) is operating an environmental restoration program to characterize, remediate, and close non-Nevada Test Site locations that were used for nuclear testing. Evaluation of radionuclide transport by groundwater from these sites is an important part of the preliminary risk analysis. These evaluations are undertaken to allow prioritization of the test areas in terms of risk, provide a quantitative basis for discussions with regulators and the public about future work at the sites, and provide a framework for assessing data needs to be filled by site characterization. The Gasbuggy site in northwestern New Mexico was the location of an underground detonation of a 29-kiloton nuclear device in 1967. The test took place in the Lewis Shale, approximately 182 m below the Ojo Alamo Sandstone, which is the aquifer closest to the detonation horizon. The conservative assumption was made that tritium was injected from the blast-created cavity into the Ojo Alamo Sandstone by the force of the explosion, via fractures created by the shot. Model results suggest that if radionuclides produced by the shot entered the Ojo Alamo, they are most likely contained within the area currently administered by DOE. The transport calculations are most sensitive to changes in the mean groundwater velocity, followed by the variance in hydraulic conductivity, the correlation scale of hydraulic conductivity, the transverse hydrodynamic dispersion coefficient, and uncertainty in the source size. This modeling was performed to investigate how the uncertainty in various physical parameters affects calculations of radionuclide transport at the Gasbuggy site, and to serve as a starting point for discussion regarding further investigation at the site; it was not intended to be a definitive simulation of migration pathways or radionuclide concentration values

Updated model for radionuclide transport in the near-surface till at Forsmark - Implementation of decay chains and sensitivity analyses

International Nuclear Information System (INIS)

Pique, Angels; Pekala, Marek; Molinero, Jorge; Duro, Lara; Trinchero, Paolo; Vries, Luis Manuel de

2013-02-01

The Forsmark area has been proposed for potential siting of a deep underground (geological) repository for radioactive waste in Sweden. Safety assessment of the repository requires radionuclide transport from the disposal depth to recipients at the surface to be studied quantitatively. The near-surface quaternary deposits at Forsmark are considered a pathway for potential discharge of radioactivity from the underground facility to the biosphere, thus radionuclide transport in this system has been extensively investigated over the last years. The most recent work of Pique and co-workers (reported in SKB report R-10-30) demonstrated that in case of release of radioactivity the near-surface sedimentary system at Forsmark would act as an important geochemical barrier, retarding the transport of reactive radionuclides through a combination of retention processes. In this report the conceptual model of radionuclide transport in the quaternary till at Forsmark has been updated, by considering recent revisions regarding the near-surface lithology. In addition, the impact of important conceptual assumptions made in the model has been evaluated through a series of deterministic and probabilistic (Monte Carlo) sensitivity calculations. The sensitivity study focused on the following effects: 1. Radioactive decay of 135 Cs, 59 Ni, 230 Th and 226 Ra and effects on their transport. 2. Variability in key geochemical parameters, such as the composition of the deep groundwater, availability of sorbing materials in the till, and mineral equilibria. 3. Variability in hydraulic parameters, such as the definition of hydraulic boundaries, and values of hydraulic conductivity, dispersivity and the deep groundwater inflow rate. The overarching conclusion from this study is that the current implementation of the model is robust (the model is largely insensitive to variations in the parameters within the studied ranges) and conservative (the Base Case calculations have a tendency to

Radionuclide behavior in water saturated porous media: Diffusion and infiltration coupling of thermodynamically and kinetically controlled radionuclide water - mineral interactions

International Nuclear Information System (INIS)

Spasennykh, M.Yu.; Apps, J.A.

1995-05-01

A model is developed describing one dimensional radionuclide transport in porous media coupled with locally reversible radionuclide water-mineral exchange reactions and radioactive decay. Problems are considered in which radionuclide transport by diffusion and infiltration processes occur in cases where radionuclide water-solid interaction are kinetically and thermodynamically controlled. The limits of Sr-90 and Cs-137 migration are calculated over a wide range of the problem variables (infiltration velocity, distribution coefficients, and rate constants of water-mineral radionuclide exchange reactions)

Transport of radionuclides in the biosphere

International Nuclear Information System (INIS)

Bundi, A.

1983-10-01

The dispersion of radionuclides in the biosphere and their uptake by man via various nutritional pathways is studied using a compartment model. The sample environment is the area of the lower Limmat and Aare valleys. General considerations of the compartmental description of the biosphere are made. The problem of the description of surface features, in particular soil, sediment and water, is studied in detail using the code BIOPATH. This study is intended to be an example of how a model of the biosphere could be constructed. It is shown that this is a reasonable model to calculate the spreading of radionuclides in the biosphere and that it indicates the relative significance of individual compartments, pathways and radionuclides. Calculated values of dose committment, however, should not be used as reference data for safety analyses. (Auth.)

Solubility limited radionuclide transport through geologic media

International Nuclear Information System (INIS)

Muraoka, Susumu; Iwamoto, Fumio; Pigford, T.H.

1980-11-01

Prior analyses for the migration of radionuclides neglect solubility limits of resolved radionuclide in geologic media. But actually some of the actinides may appear in chemical forms of very low solubility. In the present report we have proposed the migration model with no decay parents in which concentration of radionuclide is limited in concentration of solubility in ground water. In addition, the analytical solutions of the space-time-dependent concentration are presented in the case of step release, band release and exponential release. (author)

Radionuclide transport paths in the nearfield - a KBS-3 concept study

International Nuclear Information System (INIS)

Pusch, R.

1990-07-01

The general scope of the study has been to identify and define major paths for radionuclide transport from KBS3 canisters, focusing on the nearfield rock. A primary purpose was to document the hydraulic properties of the 'disturbed zones' around blasted tunnels and it is concluded from compilation of theoretical data and field experiment recording that stress relief and blasting effects combine to form a previous zone that extends to about 1 m from the tunnel periphery. It has an average, isotropic hydraulic conductivity of no less than 10 -8 m/s. A second major purpose of the study was to generalize the structure of granitic rock with respect to water-bearing fractures. Forsmark, Finnsjoen, and Stripa data have been considered and found to support the idea of rather regular 'orthogonal' fracture systems with relatively large spacings. The hydraulically active part of the fractures, which can be characterized by simple statistical distributions of persistence, spacing, and aperture, is formed by channels, which can be taken as plane, straight stripes with constant width and aperture. The width can be assumed on the basis of field observations while the aperture is estimated from the bulk conductivity and the geometry of the fracture network. The major transport paths of the rock have been concretized and combined to form a general simplified model intended for calculation of radionuclide transport through water flow and through diffusion through continuous water passages. This model comprises of a circumscribing pervious zone of 'wall disturbance' around the deposition holes in addition to the fracture channels. (author)

Colloid-Facilitated Radionuclide Transport: Current State of Knowledge from a Nuclear Waste Repository Risk Assessment Perspective

International Nuclear Information System (INIS)

Reimus, Paul William; Zavarin, Mavrik; Wang, Yifeng

2017-01-01

This report provides an overview of the current state of knowledge of colloid-facilitated radionuclide transport from a nuclear waste repository risk assessment perspective. It draws on work that has been conducted over the past 3 decades, although there is considerable emphasis given to work that has been performed over the past 3-5 years as part of the DOE Used Fuel Disposition Campaign. The timing of this report coincides with the completion of a 3-year DOE membership in the Colloids Formation and Migration (CFM) partnership, an international collaboration of scientists studying colloid-facilitated transport of radionuclides at both the laboratory and field-scales in a fractured crystalline granodiorite at the Grimsel Test Site in Switzerland. This Underground Research Laboratory has hosted the most extensive and carefully-controlled set of colloid-facilitated solute transport experiments that have ever been conducted in an in-situ setting, and a summary of the results to date from these efforts, as they relate to transport over long time and distance scales, is provided in Chapter 3 of this report.

Colloid-Facilitated Radionuclide Transport: Current State of Knowledge from a Nuclear Waste Repository Risk Assessment Perspective

Energy Technology Data Exchange (ETDEWEB)

Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wang, Yifeng [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-01-25

This report provides an overview of the current state of knowledge of colloid-facilitated radionuclide transport from a nuclear waste repository risk assessment perspective. It draws on work that has been conducted over the past 3 decades, although there is considerable emphasis given to work that has been performed over the past 3-5 years as part of the DOE Used Fuel Disposition Campaign. The timing of this report coincides with the completion of a 3-year DOE membership in the Colloids Formation and Migration (CFM) partnership, an international collaboration of scientists studying colloid-facilitated transport of radionuclides at both the laboratory and field-scales in a fractured crystalline granodiorite at the Grimsel Test Site in Switzerland. This Underground Research Laboratory has hosted the most extensive and carefully-controlled set of colloid-facilitated solute transport experiments that have ever been conducted in an in-situ setting, and a summary of the results to date from these efforts, as they relate to transport over long time and distance scales, is provided in Chapter 3 of this report.

Simplified analytical model for radionuclide transport simulation in the geosphere

International Nuclear Information System (INIS)

Hiromoto, G.

1996-01-01

In order to evaluate postclosure off-site doses from a low-level radioactive waste disposal facilities, an integrated safety assessment methodology has being developed at Instituto de Pesquisas Energeticas e Nucleares. The source-term modelling approach adopted in this system is described and the results obtained in the IAEA NSARS 'The Safety Assessment of Near-Surface Radioactive Waste Disposal Facilities' programme for model intercomparison studies are presented. The radionuclides released from the waste are calculated using a simple first order kinetics model, and the transport, through porous media below the waste is determined by using an analytical solution of the mass transport equation. The methodology and the results obtained in this work are compared with those reported by others participants of the NSARS programme. (author). 4 refs., 4 figs

Study of groundwater colloids and their ability to transport radionuclides

International Nuclear Information System (INIS)

Tjus, K.; Wikberg, P.

1987-03-01

Natural occurring colloids in groundwater can adsorb and transport released radionuclides. In this work groundwater colloids have been investigated with zeta potential measurements and dynamic light scattering. The goal was i) to estimate the detection limits of the Institute's equipment for particle size estimation with dynamic light scattering and zeta potential with dynamic light scattering combined with estimation of Doppler shift in the scattered light frequency; ii) to examine several different groundwaters (Stripa, Kamlunge, Svartboberget). The possibility to apply a theoretical adsorption model for interpreting the results is also discussed. (orig.)

Radionuclide transport in fractured rock: quantifying releases from final disposal of high level waste

International Nuclear Information System (INIS)

Silveira, Claudia S. da; Alvim, Antonio C.M.

2013-01-01

Crystalline rock has been considered as a potentially suitable matrix for high-level radioactive waste (HLW) repository because it is found in very stable geological formations and may have very low permeability. In this study the adopted physical system consists of the rock matrix containing a discrete horizontal fracture in a water saturated porous rock and a system of vertical fractures as a lineament. The transport in the fractures - horizontal and vertical, is assumed to obey a relation convection-diffusion, while the molecular diffusion is considered dominant mechanism of transport in porous rock. In this model the decay chain is considered. We use a code in Fortran 90, where the partial differential equations that describe the movement of radionuclides were discretized by finite differences methods. We use the fully implicit method for temporal discretization schemes. The simulation was performed with relevant data of nuclides in spent fuel for performance assessment in a hypothetical repository, thus quantifying the radionuclides released into the host rock. (author)

Radionuclide transport along a boreal hill slope - elevated soil water concentrations in riparian forest soils

Energy Technology Data Exchange (ETDEWEB)

Lidman, Fredrik; Boily, Aasa; Laudon, Hjalmar [Dept. of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeaa (Sweden); Koehler, Stephan J. [Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, P.O. 7050, 750 07 Uppsala (Sweden)

2014-07-01

The transport of radionuclides from forest ecosystems and out into surface waters is a crucial process for understanding the long-term fate of radionuclides in the boreal landscape. Boreal forests are typically dominated by podzol soils, but the streams draining the forests are often lined by highly organic, often peat-like soils, which the radionuclides must pass through in order to reach the stream. This so-called riparian zone therefore represents a fundamentally different biogeochemical environment than ordinary forest soils, e.g. by exhibiting significantly lower pH and higher concentrations of organic colloids, which significantly can affect the mobility of many radionuclides. Since the riparian zone is the last terrestrial environment that the groundwater is in contact with before it enters the stream, previous research has demonstrated its profound impact on the stream water chemistry. Hence, the riparian soils should also be important for the transport and accumulation of radionuclides. Therefore, soil water was sampled using suction lysimeters installed at different depths along a 22 m long forested hill slope transect in northern Sweden, following the flow pathway of the groundwater from the uphill podzol to the riparian zone near the stream channel. The analyses included a wide range of hydrochemical parameters and many radiologically important elements, e.g. U, Th, Ni, C, Sr, Cs, REEs and Cl. The sampling was repeated ten times throughout a year in order to also capture the temporal variability of the soil water chemistry. The water chemistry of the investigated transect displayed a remarkable change as the groundwater approached the stream channel. Strongly increased concentrations of many elements were observed in the riparian soils. For instance, the concentrations of Th were more than 100 times higher than in the riparian zone than in the uphill forest, suggesting that the riparian zone may be a hotspot for radionuclide accumulation. The reason

Updated model for radionuclide transport in the near-surface till at Forsmark - Implementation of decay chains and sensitivity analyses

Energy Technology Data Exchange (ETDEWEB)

Pique, Angels; Pekala, Marek; Molinero, Jorge; Duro, Lara; Trinchero, Paolo; Vries, Luis Manuel de [Amphos 21 Consulting S.L., Barcelona (Spain)

2013-02-15

The Forsmark area has been proposed for potential siting of a deep underground (geological) repository for radioactive waste in Sweden. Safety assessment of the repository requires radionuclide transport from the disposal depth to recipients at the surface to be studied quantitatively. The near-surface quaternary deposits at Forsmark are considered a pathway for potential discharge of radioactivity from the underground facility to the biosphere, thus radionuclide transport in this system has been extensively investigated over the last years. The most recent work of Pique and co-workers (reported in SKB report R-10-30) demonstrated that in case of release of radioactivity the near-surface sedimentary system at Forsmark would act as an important geochemical barrier, retarding the transport of reactive radionuclides through a combination of retention processes. In this report the conceptual model of radionuclide transport in the quaternary till at Forsmark has been updated, by considering recent revisions regarding the near-surface lithology. In addition, the impact of important conceptual assumptions made in the model has been evaluated through a series of deterministic and probabilistic (Monte Carlo) sensitivity calculations. The sensitivity study focused on the following effects: 1. Radioactive decay of {sup 135}Cs, {sup 59}Ni, {sup 230}Th and {sup 226}Ra and effects on their transport. 2. Variability in key geochemical parameters, such as the composition of the deep groundwater, availability of sorbing materials in the till, and mineral equilibria. 3. Variability in hydraulic parameters, such as the definition of hydraulic boundaries, and values of hydraulic conductivity, dispersivity and the deep groundwater inflow rate. The overarching conclusion from this study is that the current implementation of the model is robust (the model is largely insensitive to variations in the parameters within the studied ranges) and conservative (the Base Case calculations have a

PRESTO-II, Low Level Radioactive Waste Transport and Risk Assessment

International Nuclear Information System (INIS)

1990-01-01

1 - Description of program or function: PRESTO-II evaluates possible health effects from shallow-land and waste-disposal trenches. The model is intended to serve as a non- site-specific screening model for assessing radionuclide transport, ensuing exposure, and health impacts to a static local population fora 1000-year period following the end of disposal operations. Human exposure scenarios considered include normal releases (including leaching and operational spillage), human intrusion, and limited site farming or reclamation. Pathways and processes of transit from the trench to an individual or population include ground-water transport, overland flow, erosion, surface water dilution, suspension, atmospheric transport, deposition, inhalation, external exposure, and ingestion of contaminated beef, milk, crops, and water. Both population doses and individual doses, as well as doses to the intruder and farmer, may be calculated. Cumulative health effects in terms of cancer deaths are calculated for the population over the 1000-year period using a life-table approach developed by EPA (CCC-422/RADRISK). The DARTAB model is used in modified form to generate human health risk estimates from radionuclide concentrations and intake values. 2 - Method of solution: PRESTO-II tracks radionuclide transport through surface and subsurface pathways and human exposures through external exposure, inhalation, and ingestion with a resolution of 1 y. The methodology is mechanistic, and physical transport processes are modeled separately and in detail. PRESTO-II computes infiltration through the trench cap from experimentally determined permeability and hourly precipitation values. Watershed infiltration is determined using a parametric evapotranspiration equation requiring input values for several site variables. A finite element approach is used to compute trench water balance. 3 - Restrictions on the complexity of the problem: The PRESTO-II model is most appropriately used as a

Importance of biota in radionuclide transport at the SL-1 radioactive waste disposal area

International Nuclear Information System (INIS)

Arthur, W.J.; Grant, J.C.; Markham, O.D.

1983-01-01

During summer 1981 and 1982, radioecological research was conducted at the Stationary Low Power Reactor-1 radioactive waste disposal area to: (1) identify vegetation, wildlife, and invertebrate species occurring at or using the area; (2) determine radionuclide concentrations in these various ecosystem components; and (3) to evaluate their respective roles in radionuclide uptake and transport through the surrounding environment. Cesium-137 concentrations detected in surface soils, small mammal excavated soils and small mammal tissues collected at the waste disposal site were significantly (P less than or equal to 0.05) greater than control area samples. Strontium-90 and 235 U analyses of SL-1 and control area samples and projections of total mass of ecosystem components in SL-1 area will be completed in summer of 1983 at which time estimates will be made on the total quantity of fission and activation radionuclides occurring in ecological media at the SL-1 waste disposal area

Simple evaluation of groundwater flow and radionuclide transport at Aespoe

International Nuclear Information System (INIS)

Dverstorp, B.; Geier, J.; Voss, C.

1996-12-01

A simple evaluation of groundwater flux and potential for radionuclide transport at the Aespoe site, from fundamental hydrologic principles, indicates that, based upon data that are available from surface-based investigations, it is not possible to confirm that the bedrock has a high capacity to retard radionuclide release to the surface environment. This result is primarily due to the high spatial variability of hydraulic conductivity, and high uncertainty regarding the relationship among hydrologic and transport parameters within conductive elements of the bedrock. A comparison between Aespoe and seven other study sites in Sweden indicates that it is difficult or impossible to discriminate among these sites in terms of the geologic barrier function, based upon the types of data that are available from present-day methods of site characterization. Groundwater flux is evaluated by a one-dimensional application of Darcy's law to a set of simple, potential pathways for groundwater flow from the repository, which are chosen to yield an appraisal of the wide bounds of possible system behaviour. The configurations of the pathways are specified based on simple assumptions of flow-field structure, and hydraulic driving forces are specified from consideration of regional and local topographic differences. Results are expressed in terms of a parameter group that has been shown to control the barrier function. Comparisons with more detailed hydrological modelling of Aespoe show that, although a reduction in uncertainty is achieved, this reduction is not sufficient to distinguish between good and poor performance of the geologic barrier at the site. 38 refs

The Development and Application of Reactive Transport Modeling Techniques to Study Radionuclide Migration at Yucca Mountain, NV

International Nuclear Information System (INIS)

Hari Selvi Viswanathan

1999-01-01

Yucca Mountain, Nevada has been chosen as a possible site for the first high level radioactive waste repository in the United States. As part of the site investigation studies, we need to make scientifically rigorous estimations of radionuclide migration in the event of a repository breach. Performance assessment models used to make these estimations are computationally intensive. We have developed two reactive transport modeling techniques to simulate radionuclide transport at Yucca Mountain: (1) the selective coupling approach applied to the convection-dispersion-reaction (CDR) model and (2) a reactive stream tube approach (RST). These models were designed to capture the important processes that influence radionuclide migration while being computationally efficient. The conventional method of modeling reactive transport models is to solve a coupled set of multi-dimensional partial differential equations for the relevant chemical components in the system. We have developed an iterative solution technique, denoted the selective coupling method, that represents a versatile alternative to traditional uncoupled iterative techniques and the filly coupled global implicit method. We show that selective coupling results in computational and memory savings relative to these approaches. We develop RST as an alternative to the CDR method for solving large two- or three-dimensional reactive transport simulations for cases in which one is interested in predicting the flux across a specific control plane. In the RST method, the multidimensional problem is reduced to a series of one-dimensional transport simulations along streamlines. The key assumption with RST is that mixing at the control plane approximates the transverse dispersion between streamlines. We compare the CDR and RST approaches for several scenarios that are relevant to the Yucca Mountain Project. For example, we apply the CDR and RST approaches to model an ongoing field experiment called the Unsaturated Zone

Radionuclide migration in crystalline rock fractures

International Nuclear Information System (INIS)

Hoelttae, P.

2002-01-01

Crystalline rock has been considered as a host medium for the repository of high radioactive spent nuclear fuel in Finland. The geosphere will act as an ultimate barrier retarding the migration of radionuclides to the biosphere if they are released through the technical barriers. Radionuclide transport is assumed to take place along watercarrying fractures, and retardation will occur both in the fracture and within the rock matrix. To be able to predict the transport and retardation of radionuclides in rock fractures and rock matrices, it is essential to understand the different phenomena involved. Matrix diffusion has been indicated to be an important mechanism, which will retard the transport of radionuclides in rock fractures. Both dispersion and matrix diffusion are processes, which can have similar influences on solute breakthrough curves in fractured crystalline rock. In this work, the migration of radionuclides in crystalline rock fractures was studied by means of laboratory scale column methods. The purpose of the research was to gain a better understanding of various phenomena - particularly matrix diffusion - affecting the transport and retardation behaviour of radionuclides in fracture flow. Interaction between radionuclides and the rock matrix was measured in order to test the compatibility of experimental retardation parameters and transport models used in assessing the safety of underground repositories for spent nuclear fuel. Rock samples of mica gneiss and of unaltered, moderately altered and strongly altered tonalite represented different rock features and porosities offering the possibility to determine experimental boundary limit values for parameters describing both the transport and retardation of radionuclides and rock matrix properties. The dominant matrix diffusion behaviour was demonstrated in porous ceramic column and gas diffusion experiments. Demonstration of the effects of matrix diffusion in crystalline rock fracture succeeded for the

Integration into JRODOS the models of radionuclide transport in rivers, reservoirs and coastal waters to support the emergency response in early accidental stages

Energy Technology Data Exchange (ETDEWEB)

Zheleznyak, M.; Bezhenar, R.; Boyko, O.; Ievdin, I.; Koshebutsky, V.; Maderich, V. [Institute of Mathematical Machines and Systems, National Academy of Sciences of Ukraine (Ukraine); Raskob, W.; Trybushnyi, D. [Karlsruhe Institute of Technology, Institut fuer Kern- und Energietechnik (Germany)

2014-07-01

The decision support system for offsite nuclear emergency management RODOS (Real-time on-line decision support), developed under several EC RTD Framework Programs, contains many models related to support decision making in case of a nuclear or radiological emergency. Based on the request of the end users, it was re-engineered based on the JAVA technology and further named JRODOS. The consequences of the Fukushima Daiichi Nuclear Power Plant accident clearly demonstrated the importance of modeling tools predicting the radionuclide transport in marine and freshwater environment and assessing the doses to the public via the aquatic food chain to improve decision making in general. As a consequence, such an activity was launched as part of the European project PREPARE aiming to integrate the 3-dimensional model THREETOX for the radionuclide transport in coastal waters, estuaries, deep lakes, and reservoirs into hydrological model chain of JRODOS - JHDM (JRODOS Hydrological Dispersion Module). So far JHDM contains several aquatic radionuclide transport models describing the sequence of the processes 'atmospheric fallout to watershed' - 'radionuclide inflow to a river net' - 'radionuclide transport in river' - 'doses via aquatic pathways'. The implementation of the THREETOX model into this chain by developing also a user friendly interface will extend the applicability of JRODOS to deep fresh water bodies and marine coastal waters. This paper describes the assessment capabilities of this advanced model chain for two examples of the JRODOS implementation in Ukraine. JRODOS is installed in the emergency centers for two Ukrainian Nuclear Power Plants (NPP) - Zaporizzhya NPP (ZNPP) and Rivne NPP (RNPP). The different models of the JHDM were customized for these NPPs taking into account the characteristics of the water bodies in the surroundings of the NPPs. For the RNPP, located at the bank of the Sozh River which is a tributary of the

Fracture hydrology relevant to radionuclide transport. Field work in a granite formation in Cornwall

International Nuclear Information System (INIS)

Bourke, P.J.; Hodgkinson, D.P.; Durrance, E.M.; Heath, M.J.

1985-01-01

Separation, orientation, apertures and intersections of water-bearing fractures are the variables which control water flow and affect radionuclide transport through fractured rocks. The need is discussed for information on the distribution of these variables in statistical treatments of flow and transport, because of the inadequacy of permeability and porosity data in continuum treatments. Satisfactory methods of measuring distributions of separation, orientation and apetures have been developed and data for Cornish granite are presented. An estimate of the average distance between fracture intersections is made

Sorption of prioritized elements on montmorillonite colloids and their potential to transport radionuclides

International Nuclear Information System (INIS)

Wold, Susanna

2010-04-01

Due to colloids potential to bind radionuclides (RN) and even mobilise sorbed RN, colloid transport of RN should be taken into account when modeling radionuclide transport in the scenario of a leaking canister in a deep bedrock repository of spent nuclear fuel. Colloids are always present in natural waters and the concentrations are controlled by the groundwater chemistry where specifically the ionic strength is of major importance. In many deep bedrock groundwaters, the ionic strength is fairly high (above the Critical Coagulation Concentration) and therefore colloids are not likely to be stable. In these types of groundwaters colloid concentrations up to 100 μg/l could be expected, and clay colloids organic degradation products and bacteria and viruses represent can be found. In a long time perspective cycles of glaciations can be expected in Sweden as in other Nordic countries. It can not be excluded that glacial melt water can intrude to repository depth with high flows. In this scenario the groundwater conditions may drastically change. In contact with dilute groundwater the bentonite barrier can start to propagate a bentonite gel and further release montmorillonite colloids into water bearing fractures. The concentration of colloids in vicinity of the bentonite barrier can then increase drastically. In contact with Grimsel groundwater types with [Na] and [Ca] of 0.001 and 0.0001 M respectively a montmorillonite concentration of a maximum of 20 mg/l is expected. Further, the groundwater chemistry of Grimsel seems to be representative for glacial meltwater when comparing with the water chemistry data on meltwaters from existing glaciers. A key to be able to model colloid transport of radionuclides is the sorption strength and the sorption reversibility. To facilitate this, a compilation of literature K d -values and an inventory of available sorption kinetic data has been composed for the prioritized elements Pu, Th, Am, Pb, Pa, Ra, Np, Cm, Ac, Tc, Cs, Nb, Ni

Sorption of prioritized elements on montmorillonite colloids and their potential to transport radionuclides

Energy Technology Data Exchange (ETDEWEB)

Wold, Susanna (Royal Inst. of Technology, Stockholm (Sweden). School of Chemical Science and Engineering, Nuclear Chemistry)

2010-04-15

Due to colloids potential to bind radionuclides (RN) and even mobilise sorbed RN, colloid transport of RN should be taken into account when modeling radionuclide transport in the scenario of a leaking canister in a deep bedrock repository of spent nuclear fuel. Colloids are always present in natural waters and the concentrations are controlled by the groundwater chemistry where specifically the ionic strength is of major importance. In many deep bedrock groundwaters, the ionic strength is fairly high (above the Critical Coagulation Concentration) and therefore colloids are not likely to be stable. In these types of groundwaters colloid concentrations up to 100 mug/l could be expected, and clay colloids organic degradation products and bacteria and viruses represent can be found. In a long time perspective cycles of glaciations can be expected in Sweden as in other Nordic countries. It can not be excluded that glacial melt water can intrude to repository depth with high flows. In this scenario the groundwater conditions may drastically change. In contact with dilute groundwater the bentonite barrier can start to propagate a bentonite gel and further release montmorillonite colloids into water bearing fractures. The concentration of colloids in vicinity of the bentonite barrier can then increase drastically. In contact with Grimsel groundwater types with [Na] and [Ca] of 0.001 and 0.0001 M respectively a montmorillonite concentration of a maximum of 20 mg/l is expected. Further, the groundwater chemistry of Grimsel seems to be representative for glacial meltwater when comparing with the water chemistry data on meltwaters from existing glaciers. A key to be able to model colloid transport of radionuclides is the sorption strength and the sorption reversibility. To facilitate this, a compilation of literature K{sub d}-values and an inventory of available sorption kinetic data has been composed for the prioritized elements Pu, Th, Am, Pb, Pa, Ra, Np, Cm, Ac, Tc, Cs, Nb

Natural analogues and radionuclide transport model validation

International Nuclear Information System (INIS)

Lever, D.A.

1987-08-01

In this paper, some possible roles for natural analogues are discussed from the point of view of those involved with the development of mathematical models for radionuclide transport and with the use of these models in repository safety assessments. The characteristic features of a safety assessment are outlined in order to address the questions of where natural analogues can be used to improve our understanding of the processes involved and where they can assist in validating the models that are used. Natural analogues have the potential to provide useful information about some critical processes, especially long-term chemical processes and migration rates. There is likely to be considerable uncertainty and ambiguity associated with the interpretation of natural analogues, and thus it is their general features which should be emphasized, and models with appropriate levels of sophistication should be used. Experience gained in modelling the Koongarra uranium deposit in northern Australia is drawn upon. (author)

Identification and characterization of potential discharge areas for radionuclide transport by groundwater from a nuclear waste repository in Sweden.

Science.gov (United States)

Berglund, Sten; Bosson, Emma; Selroos, Jan-Olof; Sassner, Mona

2013-05-01

This paper describes solute transport modeling carried out as a part of an assessment of the long-term radiological safety of a planned deep rock repository for spent nuclear fuel in Forsmark, Sweden. Specifically, it presents transport modeling performed to locate and describe discharge areas for groundwater potentially carrying radionuclides from the repository to the surface where man and the environment could be affected by the contamination. The modeling results show that topography to large extent determines the discharge locations. Present and future lake and wetland objects are central for the radionuclide transport and dose calculations in the safety assessment. Results of detailed transport modeling focusing on the regolith and the upper part of the rock indicate that the identification of discharge areas and objects considered in the safety assessment is robust in the sense that it does not change when a more detailed model representation is used.

IN-SITU RADIONUCLIDE TRANSPORT NEAR THE NOPAL I URANIUM DEPOSIT AT PENA BLANCA, MEXICO: CONSTRAINTS FROM SHORT-LIVED DECAY-SERIES RADIONUCLIDES

International Nuclear Information System (INIS)

Luo, S.; Ku, T.L.; Todd, V.; Murrell, M.; Pineda, J. Alfredo Rodriguez; Dinsmoor, J.; Mitchell, A.

2005-01-01

For nuclear waste management, an important mechanism by which radioactive waste components are isolated from returning to the human environment, the biosphere, is by the geological barrier in which the effectiveness of the barrier is characterized by in-situ retardation factor, i.e., the transport rate of a radionuclide relative to that of groundwater. As part of natural analog studies of the Yucca Mountain Project of the U. S. Department of Energy, we propose such characterization by using naturally-occurring decay-series radioisotopes as an analog. We collected large-volume (>1000 liters) groundwater samples from three wells (PB, Pozos, and PB4, respectively) near the Nopal I Uranium Ore site at Pena Blanca, Mexico, by using an in-situ Mn-cartridge filtration technique for analysis of short-lived decay-series radionuclides. Results show that the activities of short-lived radioisotopes ( 228 Ra, 224 Ra and 223 Ra) and activity ratios of 224 Ra/ 228 Ra and 224 Ra/ 223 Ra are higher at PB and Pozos than at PB4. In contrast, the 210 Po activity is much lower at PB and Pozos than at PB4. The high Ra activities and activities ratios at PB and Pozos are attributable to the high alpha-recoil input from the aquifer rocks, while the high 210 Po activity at PB4 is due to the enhanced colloidal transport. Based on a uranium-series transport model, we estimate that the in-situ retardation factor of Ra is (0.43 ± 0.02) x 10 3 at PB, (1.68 ± 0.08) x 10 3 at Pozos, and (1.19 ± 0.08) x 10 3 at PB4 and that the mean fracture width in the aquifer rocks is about 0.23 (micro)m at PB, 0.37 (micro)m at Posos, and 4.0 (micro)m at PB4, respectively. The large fracture width at PB4 as derived from the model provides an additional evidence to the inference from the Po measurements that particle-reactive radionuclides are transported mainly as colloidal forms through the large fractures in rocks. Our model also suggests that in addition to alpha recoil, decay of 226 Ra from the adsorbed

Near-field geologic environment as an effective barrier against radionuclide transport

International Nuclear Information System (INIS)

Umeki, H.; Sakuma, H.; Ishiguro, K.; Hatanaka, K.; Naito, M.

1993-01-01

A generic performance assessment of the geologic disposal system of HLW in Japan has been carried out by the Power Reactor and Nuclear Fuel Development Corporation (PNC) in accordance with the overall HLW management program defined by the Japanese Atomic Energy Commission. A massive engineered barrier system, consisting of vitrified waste, carbon-steel overpack and thick bentonite buffer, is introduced to ensure a long-term performance of the disposal system considering a wide range of geologic environment. A major part of the total performance of the disposal system is borne by the engineered barrier system given a geologic environment that assures and complements the performance of such engineered barrier system. The performance of the natural barrier system coupled with the strong engineered barrier system was investigated by sensitivity analyses. Two types of conceptual model were considered for the analysis to describe radionuclide transport in geologic media and the range of relevant parameters was given by taking the variation of the geologic environment in Japan into account. The results show that the degree of retardation of radionuclide transport chosen in the geologic media varies significantly depending on the parameter values chosen. However, it is indicated that there are realistic combinations of those geologic parameter values which could provide a sufficient degree of retardation within a range of only a few tens of meters from the engineered barrier system. The relative importance of the near-field geologic environment is also discussed

Technical Work Plan for: Near Field Environment: Engineered System: Radionuclide Transport Abstraction Model Report

Energy Technology Data Exchange (ETDEWEB)

J.D. Schreiber

2006-12-08

This technical work plan (TWP) describes work activities to be performed by the Near-Field Environment Team. The objective of the work scope covered by this TWP is to generate Revision 03 of EBS Radionuclide Transport Abstraction, referred to herein as the radionuclide transport abstraction (RTA) report. The RTA report is being revised primarily to address condition reports (CRs), to address issues identified by the Independent Validation Review Team (IVRT), to address the potential impact of transport, aging, and disposal (TAD) canister design on transport models, and to ensure integration with other models that are closely associated with the RTA report and being developed or revised in other analysis/model reports in response to IVRT comments. The RTA report will be developed in accordance with the most current version of LP-SIII.10Q-BSC and will reflect current administrative procedures (LP-3.15Q-BSC, ''Managing Technical Product Inputs''; LP-SIII.2Q-BSC, ''Qualification of Unqualified Data''; etc.), and will develop related Document Input Reference System (DIRS) reports and data qualifications as applicable in accordance with prevailing procedures. The RTA report consists of three models: the engineered barrier system (EBS) flow model, the EBS transport model, and the EBS-unsaturated zone (UZ) interface model. The flux-splitting submodel in the EBS flow model will change, so the EBS flow model will be validated again. The EBS transport model and validation of the model will be substantially revised in Revision 03 of the RTA report, which is the main subject of this TWP. The EBS-UZ interface model may be changed in Revision 03 of the RTA report due to changes in the conceptualization of the UZ transport abstraction model (a particle tracker transport model based on the discrete fracture transfer function will be used instead of the dual-continuum transport model previously used). Validation of the EBS-UZ interface model

Study of the hydrodynamic circulation and transport of radionuclides in the Ilha Grande Bay -RJ

International Nuclear Information System (INIS)

Franklin, Mariza Ramalho

2001-01-01

The Almirante Alvaro Alberto Nuclear Center (CNAAA), located at the city of Rio de Janeiro and the liquid effluents are released into the Ilha Grande Bay (BIG). The objective of this work was to simulate mathematically the dispersion of 3 H and 137 Cs present in the liquid effluents that are routinely released into the environment, and in this way contribute to the improvement of the radiological impact assessment associated to these releases. The hydrodynamic circulation pattern of the bay and the transport of radionuclides were simulated by means of numerical modeling techniques by the computational system SisBAHIA (Sistema Base Hidrodinâmica e Ambiental). The results indicate that the local circulation pattern is mainly driven by the propagation of the tidal wave, and is characterized by low current velocities of about 0.1 m.s -1 . The wind stress (normal or extreme ones ) over the free surface does not alter the local circulation pattern significantly. The effluents are released in a rate of about 120 m 3 .s. -1 . As a result, the local hydrodynamics is markedly altered by means of the formation of a huge vortices close to the release area. According to the annual amount of the released radionuclides predicted in the Nuclear Licensing Document, and considering a continuous release it could be predicted that the radionuclide plume would present a low mobility, with most of the activity concentration amount being restricted close to the source. The activity concentration distribution reach the transportation steady state by the end of the 51 st day of simulation. A conservative behavior of both radionuclides in the water column was assumed in the performed simulation. (author)

Application of two-barrier model of radioactive agent transport in sea water for analyzing artificial radionuclide release from containers with radioactive waste dumped in Kara Sea

Energy Technology Data Exchange (ETDEWEB)

Grishin, Denis S.; Laykin, Andrey I.; Kuchin, Nickolay L.; Platovskikh, Yuri A. [Krylov State Research Center, Saint Petersburg, 44 Moskovskoe shosse, 196158 (Russian Federation)

2014-07-01

Modeling of artificial radionuclide transport in sea water is crucial for prognosis of radioecological situation in regions where dumping of radioactive waste had been made and/or accidents with nuclear submarines had taken place. Distribution of artificial radionuclides in bottom sediments can be a detector of radionuclide release from dumped or sunk objects to marine environment. Proper model can determine the dependence between radionuclide distribution in sediments and radionuclide release. Following report describes two-barrier model of radioactive agent transport in sea water. It was tested on data from 1994 - 2013 expeditions to Novaya Zemlya bays, where regular dumping of solid radioactive waste was practiced by the former USSR from the early 1960's until 1990. Two-barrier model agrees with experimental data and allows more accurate determination of time and intensity of artificial radionuclide release from dumped containers. (authors)

Transport of fallout and reactor radionuclides in the drainage basin of the Hudson River estuary

International Nuclear Information System (INIS)

Simpson, H.J.; Linsalata, P.; Olsen, C.R.

1982-01-01

The transport and fate of Strontium 90, Cesium 137 and Plutonium 239, 240 in the Hudson River Estuary is discussed. Rates of radionuclide deposition and accumulation over time and space are calculated for the Hudson River watershed, estuary, and continental shelf offshore. 37 references, 7 figures, 15 tables

Evaluation of selected predictive models and parameters for the environmental transport and dosimetry of radionuclides

International Nuclear Information System (INIS)

Miller, C.W.; Dunning, D.E. Jr.; Etnier, E.L.; Hoffman, F.O.; Little, C.A.; Meyer, H.R.; Shaeffer, D.L.; Till, J.E.

1979-07-01

Evaluations of selected predictive models and parameters used in the assessment of the environmental transport and dosimetry of radionuclides are summarized. Mator sections of this report include a validation of the Gaussian plume disperson model, comparison of the output of a model for the transport of 131 I from vegetation to milk with field data, validation of a model for the fraction of aerosols intercepted by vegetation, an evaluation of dose conversion factors for 232 Th, an evaluation of considering the effect of age dependency on population dose estimates, and a summary of validation results for hydrologic transport models

The role of colloids and suspended particles in radionuclide transport in the Canadian concept for nuclear fuel waste disposal

International Nuclear Information System (INIS)

Vilks, P.

1994-02-01

AECL Research is developing a concept for the permanent disposal of nuclear fuel waste in a deep engineered vault in plutonic rock of the Canadian Shield and is preparing an Environmental Impact Statement (EIS) to document its case for the acceptability of the disposal concept. This report, one in a series of supporting documents for the EIS, addresses the role of particles in radionuclide transport. It summarizes our studies of natural particles in groundwater and presents the arguments used to justify the omission of particle-facilitated transport in the geosphere model that is based on the Whiteshell Research Area (WRA) and used in the postclosure assessment study case. Because radiocolloids formed in the vault will not be able to migrate through the clay buffer, radiocolloid formation in the geosphere will be determined by the sorption of radionuclides onto particles in groundwater. These particles consist of typical fracture-lining minerals, such as clays, micas and quartz; precipitated particles, such as colloidal silica and Fe-Si oxyhydroxides; and organic particles. In groundwater from the WRA, the average concentrations of colloids and suspended particles are 0.34 and 1.4 mg/L respectively. Particle-facilitated transport is not included in the geosphere model because the concentrations of particles in groundwater from the WRA are too low to have a significant impact on radionuclide transport. (author). 92 refs., 11 tabs., 13 figs

Radionuclide daughter inventory generator code: DIG

International Nuclear Information System (INIS)

Fields, D.E.; Sharp, R.D.

1985-09-01

The Daughter Inventory Generator (DIG) code accepts a tabulation of radionuclide initially present in a waste stream, specified as amounts present either by mass or by activity, and produces a tabulation of radionuclides present after a user-specified elapsed time. This resultant radionuclide inventory characterizes wastes that have undergone daughter ingrowth during subsequent processes, such as leaching and transport, and includes daughter radionuclides that should be considered in these subsequent processes or for inclusion in a pollutant source term. Output of the DIG code also summarizes radionuclide decay constants. The DIG code was developed specifically to assist the user of the PRESTO-II methodology and code in preparing data sets and accounting for possible daughter ingrowth in wastes buried in shallow-land disposal areas. The DIG code is also useful in preparing data sets for the PRESTO-EPA code. Daughter ingrowth in buried radionuclides and in radionuclides that have been leached from the wastes and are undergoing hydrologic transport are considered, and the quantities of daughter radionuclide are calculated. Radionuclide decay constants generated by DIG and included in the DIG output are required in the PRESTO-II code input data set. The DIG accesses some subroutines written for use with the CRRIS system and accesses files containing radionuclide data compiled by D.C. Kocher. 11 refs

A simplified model for calculating atmospheric radionuclide transport and early health effects from nuclear reactor accidents

International Nuclear Information System (INIS)

Madni, I.K.; Cazzoli, E.G.; Khatib-Rahbar, M.

1995-01-01

During certain hypothetical severe accidents in a nuclear power plant, radionuclides could be released to the environment as a plume. Prediction of the atmospheric dispersion and transport of these radionuclides is important for assessment of the risk to the public from such accidents. A simplified PC-based model was developed that predicts time-integrated air concentration of each radionuclide at any location from release as a function of time integrated source strength using the Gaussian plume model. The solution procedure involves direct analytic integration of air concentration equations over time and position, using simplified meteorology. The formulation allows for dry and wet deposition, radioactive decay and daughter buildup, reactor building wake effects, the inversion lid effect, plume rise due to buoyancy or momentum, release duration, and grass height. Based on air and ground concentrations of the radionuclides, the early dose to an individual is calculated via cloudshine, groundshine, and inhalation. The model also calculates early health effects based on the doses. This paper presents aspects of the model that would be of interest to the prediction of environmental flows and their public consequences

Radionuclide transport in the Neogene aquifer system located in the environment of the Boom clay

International Nuclear Information System (INIS)

Gedeon, M.; Marivoet, J.; Vandersteen, K.

2012-01-01

Document available in extended abstract form only. In the framework the Belgian research program on the long term management of high-level and/or long-lived radioactive waste coordinated by ONDRAF/NIRAS, the Boom Clay is considered as a reference host rock for the geological disposal of high-level radioactive waste in NE-Belgium (Campine area). In the frame of the performance assessments of a disposal system located in the Boom Clay Formation, the transport of radionuclides diffusing through the clay barrier into the aquifers located above is modelled. The transport model for the Neogene aquifer is based on a series of groundwater flow models simulating the aquifer systems in the surroundings of the Boom Clay. This series of groundwater models include the regional north-eastern Belgium model simulating flow both above and below the Boom Clay, the recently updated deep-aquifer pumping model, simulating transient flow in the over-exploited aquifers below the Boom Clay and finally the catchment-scale Neogene aquifer model, simulating flow in the aquifer system above the Boom Clay. The Neogene aquifer system consists of two main aquifers. The Pliocene aquifer is located at the top, separated from the underlying Miocene aquifer by the Kasterlee Clay aquitard. The Miocene aquifer consists of three hydrostratigraphic units: the Diest, Berchem and Voort Formations; with the last two having a lower hydraulic conductivity than the Diest unit. The transport model for the Neogene aquifer represents a fraction of the catchment-scale Neogene aquifer model. It stretches from the local divide between the Grote and Kleine Nete Rivers up to the Kleine Nete River, representing the main model sink. The boundary conditions and the sources/sinks in the Pliocene aquifer are defined mostly by the surface water features, such as the rivers, brooks, lakes and canals. In the partially confined Miocene aquifer, the effect of the surface water features is dampened and the heads at the model

Transport of radionuclides from the LAMPF lagoons

International Nuclear Information System (INIS)

Ferenbaugh, R.W.; Purtymun, W.D.

1985-01-01

Monitoring of the discharge water from the Los Alamos Meson Physics Facility lagoons continued during June and December of 1983. The list of radionuclides being monitoring includes 7 Be, 57 Co, 134 Cs, 3 H, 54 Mn, 22 Na, and 83 Rb. The sampling locations and the data obtained to date are presented. Movement of radionuclides around the lagoons has been described in a previous report. 1 reference, 1 table

Modelling of radionuclide transport along the underground access structures of deep geological repositories

Energy Technology Data Exchange (ETDEWEB)

Poller, A. [National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen (Switzerland); Smith, P. [SAM Switzerland GmbH, Zuerich (Switzerland); Mayer, G.; Hayek, M. [AF-Consult Switzerland AG, Baden (Switzerland)

2014-08-15

The arrangement and sealing of the access routes to a deep geological repository for radioactive waste should ensure that any radionuclide release from the emplacement rooms during the post closure phase does not by-pass the geological barriers of the repository system to a significant extent. The base case of the present study, where realistic values for the hydraulic properties of the seals and the associated excavation damage zones were assumed, assesses to what extent this is actually the case for different layout variants (ramp and shaft access and shaft access only). Furthermore, as a test of robustness of system performance against uncertainties related to such seals and the associated excavation damage zones, the present study also considers a broad spectrum of calculation cases including the hypothetical possibility that the seals perform much more poorly than expected and to check whether, consequently, the repository tunnel system and the access structures may provide significant release pathways. The study considers a generic repository system for high-level waste (HLW repository) and for low- and intermediate-level waste (L/ILW repository), both with Opalinus Clay as the host rock. It also considers the alternative possibilities of a ramp or a shaft as the access route for material transport (waste packages, etc.) to the underground facilities. Additional shafts, e.g. for the transport of persons and for ventilation, are included in both cases. The overall modelling approach consists of three broad steps: (a) the network of tunnels and access structures is implemented in a flow model, which serves to calculate water flow rates along the tunnels and through the host rock; (b) all relevant transport paths are implemented in a radionuclide release and transport model, the water flow rates being obtained from the preceding flow model calculations; (c) individual effective dose rates arising from the radionuclides released from the considered repository

Marine radionuclide transport in the northern North Atlantic estimated with an eddy-permitting ocean model - Marine radionuclide transport in the Northern North Atlantic estimated with an Eddy-resolving ocean model

Energy Technology Data Exchange (ETDEWEB)

Simonsen, Magne [Norwegian Meteorological institute, P.O. Box 43 Blindern, N-0313 Oslo (Norway); Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Aas (Norway); Isachsen, Paal E.; Saetra, Oeyvind; Klein, Heiko; Bartnicki, Jerzy [Norwegian Meteorological institute, P.O. Box 43 Blindern, N-0313 Oslo (Norway); Salbu, Brit; Lind, Ole C. [Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Aas (Norway)

2014-07-01

As a part of the Norwegian Centre for Environmental Radioactivity (CERAD), we have studied transport of radionuclides in the Nordic Seas using an eddy-resolving ocean model. Transport and dispersion is estimated by both Lagrangian (particle) and Eulerian (tracer) methods using currents generated by the Regional Ocean Model System (ROMS) at 4 km horizontal resolution. This relatively high resolution gives a more accurate description of the impact of macro-turbulent advection on transport paths and transport times than achieved in previous studies. The experiments cover historical discharges from the Sellafield reprocessing plant as well as hypothetical accident scenarios from power plants in Great Britain. For the historical Sellafield discharges, model calculations are compared to isotope concentrations observed along the Norwegian Coast and in the Barents Sea. For the accident scenarios, the likely impact on the Norwegian coastal zone is studied considering three different sources for the ocean: direct local discharge, far-field deposition from the atmosphere, and discharge via Norwegian rivers (via atmospheric deposition over land). (authors)

Transport of radionuclides in stochastic media. Pt. 1: The quasi-asymptotic approximation

International Nuclear Information System (INIS)

Devooght, J.; Smidts, O.F.

1996-01-01

A three-dimensional quasi-asymptotic approximate equation is developed for the transport of radionuclides in a stochastic velocity field. This approximation is derived from an integro-differential equation of transport in stochastic media, commonly encountered in hydrogeology. The quasi-asymptotic equation turns out to be a generalised Telegrapher's equation as found by Williams in the particular context of fractured media. We obtain the Telegrapher's equation without specifying the causes responsible for the random velocity field. Our model may thus be applied in porous media as well as in fractured media. We give the developments leading to the analytical solution of the three-dimensional Telegrapher's equation for constant parameters. This solution is then visualised for a source in the form of a square wave. (Author)

Radionuclides in the study of marine processes

International Nuclear Information System (INIS)

Kershaw, P.J.; Woodhead, D.S.

1991-01-01

For many years, the radioactive properties of the naturally occurring radionuclides have been used to determine their distributions in the marine environment and, more generally, to gain an understanding of the dynamic processes which control their behaviour in attaining these distributions. More recently the inputs from human activities of both natural and artificial (i.e. man-made) radionuclides have provided additional opportunities for the study of marine processes on local, regional and global scales. The primary objective of the symposium is to provide a forum for an open discussion of the insights concerning processes in the marine environment which can be gained from studies of radionuclide behaviour. Papers have been grouped within the following principal themes; the uses of radionuclides as tracers of water transport; scavenging and particulate transport processes in the oceans as deduced from radionuclide behaviour; processes in the seabed and radionuclides in biological systems. (Author)

Chemical speciation of radionuclides migrating in groundwaters

International Nuclear Information System (INIS)

Robertson, D.; Schilk, A.; Abel, K.; Lepel, E.; Thomas, C.; Pratt, S.; Cooper, E.; Hartwig, P.; Killey, R.

1994-04-01

In order to more accurately predict the rates and mechanisms of radionuclide migration from low-level waste disposal facilities via groundwater transport, ongoing studies are being conducted at field sites at Chalk River Laboratories to identify and characterize the chemical speciation of mobile, long-lived radionuclides migrating in groundwaters. Large-volume water sampling techniques are being utilized to separate and concentrate radionuclides into particular, cationic, anionic, and nonionic chemical forms. Most radionuclides are migrating as soluble, anionic species that appear to be predominantly organoradionuclide complexes. Laboratory studies utilizing anion exchange chromatography have separated several anionically complexed radionuclides, e.g., 60 Co and 106 Ru, into a number of specific compounds or groups of compounds. Further identification of the anionic organoradionuclide complexes is planned utilizing high resolution mass spectrometry. Large-volume ultra-filtration experiments are characterizing the particulate forms of radionuclides being transported in these groundwaters

Assessment of hydrologic transport of radionuclides from the Gnome underground nuclear test site, New Mexico

International Nuclear Information System (INIS)

Earman, S.; Chapman, J.; Pohlmann, K.; Andricevic, R.

1996-09-01

The U.S. Department of Energy (DOE) is operating an environmental restoration program to characterize, remediate, and close non-Nevada Test Site locations that were used for nuclear testing. Evaluation of radionuclide transport by groundwater from these sites is an important part of the preliminary site risk analysis. These evaluations are undertaken to allow prioritization of the test areas in terms of risk, provide a quantitative basis for discussions with regulators and the public about future work at the sites, and provide a framework for assessing data needs to be filled by site characterization. The Gnome site in southeastern New Mexico was the location of an underground detonation of a 3.5-kiloton nuclear device in 1961, and a hydrologic tracer test using radionuclides in 1963. The tracer test involved the injection of tritium, 90 Sr, and 137 Cs directly into the Culebra Dolomite, a nine to ten-meter-thick aquifer located approximately 150 in below land surface. The Gnome nuclear test was carried out in the Salado Formation, a thick salt deposit located 200 in below the Culebra. Because salt behaves plastically, the cavity created by the explosion is expected to close, and although there is no evidence that migration has actually occurred, it is assumed that radionuclides from the cavity are released into the overlying Culebra Dolomite during this closure process. Transport calculations were performed using the solute flux method, with input based on the limited data available for the site. Model results suggest that radionuclides may be present in concentrations exceeding drinking water regulations outside the drilling exclusion boundary established by DOE. Calculated mean tritium concentrations peak at values exceeding the U.S. Environmental Protection Agency drinking water standard of 20,000 pCi/L at distances of up to almost eight kilometers west of the nuclear test

Assessment of the important radionuclides in nuclear waste

International Nuclear Information System (INIS)

Kerrisk, J.F.

1985-10-01

The relative importance of the various radionuclides contained in nuclear waste has been assessed by consideration of (1) the quantity of each radionuclide present, (2) the Environmental Protection Agency's release limits for radionuclides, (3) how retardation processes such as solubility and sorption affect radionuclie transport, and (4) the physical and chemical forms of radionuclides in the waste. Three types of waste were reviewed: spent fuel, high-level waste, and defense high-level waste. Conditions specific to the Nevada Nuclear Waste Storage Investigations project potential site at Yucca Mountain were used to describe radionuclide transport. The actinides Am, Pu, Np, and U were identified as the waste elements for which solubility and sorption data were most urgently needed. Other important waste elements were identified as Sr, Cs, C, Ni, Zr, Tc, Th, Ra, and Sn. Under some conditions, radionuclides of three elements (C, Tc, and I) may have high solubility and negligible sorption. The potential for transport of some waste elements (C and I) in the gas phase must also be evaluated for the Yucca Mountain Site. 12 refs., 17 tabs

Final Technical Report: Viral Infection of Subsurface Microorganisms and Metal/Radionuclide Transport

Energy Technology Data Exchange (ETDEWEB)

Weber, Karrie A.; Bender, Kelly S.; Li, Yusong

2013-09-28

Microbially mediated metabolisms have been identified as a significant factor either directly or indirectly impacting the fate and transport of heavy metal/radionuclide contaminants. To date microorganisms have been isolated from contaminated environments. Examination of annotated finished genome sequences of many of these subsurface isolates from DOE sites, revealed evidence of prior viral infection. To date the role that viruses play influencing microbial mortality and the resulting community structure which directly influences biogeochemical cycling in soils and sedimentary environments remains poorly understood. The objective of this exploratory study was to investigate the role of viral infection of subsurface bacteria and the formation of contaminant-bearing viral particles. This objective was approached by examining the following working hypotheses: (i) subsurface microorganisms are susceptible to viral infections by the indigenous subsurface viral community, and (ii) viral surfaces will adsorb heavy metals and radionuclides. Our results have addressed basic research needed to accomplish the BER Long Term Measure to provide sufficient scientific understanding such that DOE sites would be able to incorporate coupled physical, chemical and biological processes into decision making for environmental remediation or natural attenuation and long-term stewardship by establishing viral-microbial relationships on the subsequent fate and transport of heavy metals and radionuclides. Here we demonstrated that viruses play a significant role in microbial mortality and community structure in terrestrial subsurface sedimentary systems. The production of viral-like particles within subsurface sediments in response to biostimulation with dissolved organic carbon and a terminal electron acceptor resulted in the production of viral-like particles. Organic carbon alone did not result in significant viral production and required the addition of a terminal electron acceptor

IN-SITU RADIONUCLIDE TRANSPORT NEAR THE NOPAL I URANIUM DEPOSIT AT PENA BLANCA, MEXICO: CONSTRAINTS FROM SHORT-LIVED DECAY-SERIES RADIONUCLIDES

Energy Technology Data Exchange (ETDEWEB)

S. Luo; T.L. Ku; V. Todd; M. Murrell; J. Alfredo Rodriguez Pineda; J. Dinsmoor; A. Mitchell

2005-07-11

For nuclear waste management, an important mechanism by which radioactive waste components are isolated from returning to the human environment, the biosphere, is by the geological barrier in which the effectiveness of the barrier is characterized by in-situ retardation factor, i.e., the transport rate of a radionuclide relative to that of groundwater. As part of natural analog studies of the Yucca Mountain Project of the U. S. Department of Energy, we propose such characterization by using naturally-occurring decay-series radioisotopes as an analog. We collected large-volume (>1000 liters) groundwater samples from three wells (PB, Pozos, and PB4, respectively) near the Nopal I Uranium Ore site at Pena Blanca, Mexico, by using an in-situ Mn-cartridge filtration technique for analysis of short-lived decay-series radionuclides. Results show that the activities of short-lived radioisotopes ({sup 228}Ra, {sup 224}Ra and {sup 223}Ra) and activity ratios of {sup 224}Ra/{sup 228}Ra and {sup 224}Ra/{sup 223}Ra are higher at PB and Pozos than at PB4. In contrast, the {sup 210}Po activity is much lower at PB and Pozos than at PB4. The high Ra activities and activities ratios at PB and Pozos are attributable to the high alpha-recoil input from the aquifer rocks, while the high {sup 210}Po activity at PB4 is due to the enhanced colloidal transport. Based on a uranium-series transport model, we estimate that the in-situ retardation factor of Ra is (0.43 {+-} 0.02) x 10{sup 3} at PB, (1.68 {+-} 0.08) x 10{sup 3} at Pozos, and (1.19 {+-} 0.08) x 10{sup 3} at PB4 and that the mean fracture width in the aquifer rocks is about 0.23 {micro}m at PB, 0.37 {micro}m at Posos, and 4.0 {micro}m at PB4, respectively. The large fracture width at PB4 as derived from the model provides an additional evidence to the inference from the Po measurements that particle-reactive radionuclides are transported mainly as colloidal forms through the large fractures in rocks. Our model also suggests that

Technical Work Plan for: Near Field Environment: Engineered Barrier System: Radionuclide Transport Abstraction Model Report

International Nuclear Information System (INIS)

J.D. Schreiber

2006-01-01

This technical work plan (TWP) describes work activities to be performed by the Near-Field Environment Team. The objective of the work scope covered by this TWP is to generate Revision 03 of EBS Radionuclide Transport Abstraction, referred to herein as the radionuclide transport abstraction (RTA) report. The RTA report is being revised primarily to address condition reports (CRs), to address issues identified by the Independent Validation Review Team (IVRT), to address the potential impact of transport, aging, and disposal (TAD) canister design on transport models, and to ensure integration with other models that are closely associated with the RTA report and being developed or revised in other analysis/model reports in response to IVRT comments. The RTA report will be developed in accordance with the most current version of LP-SIII.10Q-BSC and will reflect current administrative procedures (LP-3.15Q-BSC, ''Managing Technical Product Inputs''; LP-SIII.2Q-BSC, ''Qualification of Unqualified Data''; etc.), and will develop related Document Input Reference System (DIRS) reports and data qualifications as applicable in accordance with prevailing procedures. The RTA report consists of three models: the engineered barrier system (EBS) flow model, the EBS transport model, and the EBS-unsaturated zone (UZ) interface model. The flux-splitting submodel in the EBS flow model will change, so the EBS flow model will be validated again. The EBS transport model and validation of the model will be substantially revised in Revision 03 of the RTA report, which is the main subject of this TWP. The EBS-UZ interface model may be changed in Revision 03 of the RTA report due to changes in the conceptualization of the UZ transport abstraction model (a particle tracker transport model based on the discrete fracture transfer function will be used instead of the dual-continuum transport model previously used). Validation of the EBS-UZ interface model will be revised to be consistent with

Conceptual and Numerical Modeling of Radionuclide Transport and Retention in Near-Surface Systems

International Nuclear Information System (INIS)

Pique, Angels; Arcos, David; Grandia, Fidel; Molinero, Jorge; Duro, Lara; Berglund, Sten

2013-01-01

Scenarios of barrier failure and radionuclide release to the near-surface environment are important to consider within performance and safety assessments of repositories for nuclear waste. A geological repository for spent nuclear fuel is planned at Forsmark, Sweden. Conceptual and numerical reactive transport models were developed in order to assess the retention capacity of the Quaternary till and clay deposits for selected radionuclides, in the event of an activity release from the repository. The elements considered were carbon (C), chlorine (Cl), cesium (Cs), iodine (I), molybdenum (Mo), niobium (Nb), nickel (Ni), radium (Ra), selenium (Se), strontium (Sr), technetium (Tc), thorium (Th), and uranium (U). According to the numerical predictions, the repository-derived nuclides that would be most significantly retained are Th, Ni, and Cs, mainly through sorption onto clays, followed by U, C, Sr, and Ra, trapped by sorption and/or incorporation into mineral phases

Transport of oxidants and radionuclides through a clay barrier

International Nuclear Information System (INIS)

Neretnieks, I.

1978-02-01

The masstransfer rate for oxidants to, and radionuclides from a capsule in a repository has been computed. The capsule which is 0.75 m in diameter is surrounded by Montmorillonite clay. The hole is 1.5 m in diameter. For one capsule about 1220g copper will corrode due to oxygen corrosion in 10 000 years. If the fissures in the rock nearest the hole are filled with clay, the corrosion will decrease significantly. This is valid for a case where the groundwater is in equilibrium with oxygen of 0.2 bar pressure (normal air pressure). Measurements of the oxygen content in groundwater at large depths show a more than 1 000 times smaller values. The transport rate will then be correspondingly smaller. Corrosion due to sulphate/sulphide corrosion may reach some 590 g in the same time if there is 10 mg/l of the least abundant component. The radionuclides Sr 90 , Cs 137 , Am 241 and Am 243 will decay totally in the clay barriers. Pu 240 will be seriously hindered. The total dissolution of the uranium oxide in a capsule takes at least 1.8 million years. Nuclides with high solubilities decrease in about 2 000 years to half their original concentration. The sodium in the Montmorillonite clay in the fissures is exchanged for calcium in about 20 000 years. The exchange of the sodium in the clay in the hole takes millions of years

Sediment and radionuclide transport in rivers. Phase 3. Field sampling program for Cattaraugus and Buttermilk Creeks, New York

International Nuclear Information System (INIS)

Ecker, R.M.; Walters, W.H.; Onishi, Y.

1982-08-01

A field sampling program was conducted on Cattaraugus and Buttermilk Creeks, New York during April 1979 to investigate the transport of radionuclides in surface waters as part of a continuing program to provide data for application and verification of Pacific Northwest Laboratory's (PNL) sediment and radionuclide transport model, SERATRA. Bed sediment, suspended sediment and water samples were collected during unsteady flow conditions over a 45 mile reach of stream channel. Radiological analysis of these samples included gamma ray spectrometry analysis, and radiochemical separation and analysis of Sr-90, Pu-238, Pu-239, 240, Am-241 and Cm-244. Tritium analysis was also performed on water samples. Based on the evaluation of radionuclide levels in Cattaraugus and Buttermilk Creeks, the Nuclear Fuel Services facility at West Valley, New York, may be the source of Cs-137, Sr-90, Cs-134, Co-60, Pu-238, Pu-239, 240, Am-241, Cm-244 and tritium found in the bed sediment, suspended sediment and water of Buttermilk and Cattaraugus Creeks. This field sampling effort was the last of a three phase program to collect hydrologic and radiologic data at different flow conditions

Modeling studies of mountain-scale radionuclide transport in the unsaturated zone at Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Moridis, George J.; Seol, Yongkoo; Wu, Yu-Shu

2003-01-01

We investigate radionuclide transport from a high-level nuclear waste repository to be situated in the unsaturated zone (UZ) at Yucca Mountain (YM), Nevada. Several radioactive solutes (that cover the range of sorption behavior) and colloids of various sizes are studied. The results of the study indicate the importance of the subsurface geology and site hydrology, i.e., the presence of faults (they dominate and control transport), fractures (the main migration pathways), and the relative distribution of zeolitic and vitric tuffs. The effects of the climatic conditions, diffusion, and sorption (for solutes) or infiltration (for colloids) onto the matrix are discussed. The influence of the colloid size on transport is also investigated

Modeling the Hydrogeochemical Transport of Radionuclides through Engineered Barriers System in the Proposed LLW Disposal Site of Taiwan - 12082

Energy Technology Data Exchange (ETDEWEB)

Lin, Wen-Sheng [Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan (China); Liu, Chen-Wuing; Tsao, Jui-Hsuan [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, Taiwan (China); Li, Ming-Hsu [Institute of Hydrological and Oceanic Sciences, National Central University, Jhongli, Taiwan (China)

2012-07-01

A proposed site for final disposal of low-level radioactive waste located in Daren Township of Taitung County along the southeastern coast has been on the selected list in Taiwan. The geology of the Daren site consists of argillite and meta-sedimentary rocks. A mined cavern design with a tunnel system of 500 m below the surface is proposed. Concrete is used as the main confinement material for the engineered barrier. To investigate the hydrogeochemical transport of radionuclides through engineered barriers system, HYDROGEOCHEM5.0 model was applied to simulate the complex chemical interactions among radionuclides, the cement minerals of the concrete, groundwater flow, and transport in the proposed site. The simulation results showed that the engineered barriers system with the side ditch efficiently drained the ground water and lowered the concentration of the concrete degradation induced species (e.g., hydrogen ion, sulfate, and chloride). The velocity of groundwater observed at side ditch gradually decreased with time due to the fouling of pore space by the mineral formation of ettringite and thaumasite. The short half-life of Co-60, Sr-90 and Cs-137 significantly reduced the concentrations, whereas the long half-life of I-129(1.57x10{sup 7} years) and Am-241(432 years) remain stable concentrations at the interface of waste canister and concrete barrier after 300 years. The mineral saturation index (SI) was much less than zero due to the low aqueous concentration of radionuclide, so that the precipitation formation of Co-60, Sr-90, I-129, Cs-137 and Am-241 related minerals were not found. The effect of adsorption/desorption (i.e., surface complexation model) could be a crucial geochemical mechanism for the modeling of liquid-solid phase behavior of radionuclide in geochemically dynamic environments. Moreover, the development of advanced numerical models that are coupled with hydrogeochemical transport and dose assessment of radionuclide is required in the future

The role of colloids in the transport of radionuclides in geological media

International Nuclear Information System (INIS)

Moulin, V.

1993-01-01

The main objective of this programme is to understand how colloids could influence the migration behaviour of radionuclides in geological formations. This is being achieved firstly, by identifying the retention mechanisms of colloids and pseudocolloids (association of radionuclides with colloids) on mineral surfaces by static and dynamic experiments, and secondly by investigating the formation of pseudocolloids. Moreover, these studies will be focused on model systems (surfaces, colloids) selected from studies carried out on the El Berrocal site (characterization of the granite, of the colloids). Two types of experiments are planned: for the study of pseudocolloid formation, sorption experiments (batch tests) with radionuclides will be conducted either with model inorganic colloidal suspensions or with mineral monoliths as macroscopic surfaces of colloids. Dynamic experiments will be performed using well-defined packings of both synthetic and natural minerals (major constituents of granite). Moreover, a particular attention will be devoted to the organic coatings (in static and dynamic conditions). These studies will provide data directly usable by migration models to predict colloid transport under conditions relevant to geological disposals. This programme will be carried out in collaboration with the different partners of this contract: CEA (Fontenay-aux-Roses/F), CIEMAT (Madrid/S), CNRS (Orsay/F), GERMETRAD (Nantes/F), GSF (Munich/G), INFM (Padua/I), INTERA (London/UK) with Dr V. Moulin, Dr P. Rivas, Dr J.C. Dran, Pr Pieri, Dr C. Wolfrum, Pr G. Della Mea and Dr P. Grindrod as project leaders respectively. 4 refs., 2 figs., 1 tab

COLLOID-FACILITATED TRANSPORT OF RADIONUCLIDES THROUGH THE VADOSE ZONE

International Nuclear Information System (INIS)

Flury, Markus

2003-01-01

close relations to the following EMSP projects: Project: 70126, Interfacial Soil Chemistry of Radionuclides in the Unsaturated Zone (PI: Jon Chorover) Project: 70070, Reactivity of Primary Soil Minerals and Secondary Precipitates (PI: Kathy Nagy) Cesium Transport in Hanford Sediments: Application of an Experimentally Based Cation Exchange Model (PI: Susan Carroll and Carl Steefel)

Uranium and Cesium sorption to bentonite colloids in high salinity and carbonate-rich environments: Implications for radionuclide transport

Science.gov (United States)

Tran, E. L.; Teutsch, N.; Klein-BenDavid, O.; Weisbrod, N.

2017-12-01

When radionuclides are leaked into the subsurface due to engineered waste disposal container failure, the ultimate barrier to migration of radionuclides into local aquifers is sorption to the surrounding rock matrix and sediments, which often includes a bentonite backfill. The extent of this sorption is dependent on pH, ionic strength, surface area availability, radionuclide concentration, surface mineral composition, and solution chemistry. Colloidal-sized bentonite particles eroded from the backfill have been shown to facilitate the transport of radionuclides sorbed to them away from their source. Thus, sorption of radionuclides such as uranium and cesium to bentonite surfaces can be both a mobilization or retardation factor. Though numerous studies have been conducted to-date on sorption of radionuclides under low ionic strength and carbonate-poor conditions, there has been little research conducted on the behavior of radionuclides in high salinities and carbonate rich conditions typical of aquifers in the vicinity of some potential nuclear repositories. This study attempts to characterize the sorption properties of U(VI) and Cs to bentonite colloids under these conditions using controlled batch experiments. Results indicated that U(VI) undergoes little to no sorption to bentonite colloids in a high-salinity (TDS= 9000 mg/L) artificial groundwater. This lack of sorption was attributed to the formation of CaUO2(CO3)22- and Ca2UO2(CO3)3 aqueous ions which stabilize the UO22+ ions in solution. In contrast, Cs exhibited greater sorption, the extent to which was influenced greatly by the matrix water's ionic strength and the colloid concentration used. Surprisingly, when both U and Cs were together, the presence of U(VI) in solution decreased Cs sorption, possibly due to the formation of stabilizing CaUO2(CO3)22- anions. The implications of this research are that rather than undergoing colloid-facilitated transport, U(VI) is expected to migrate similarly to a

Modeling of radionuclide transport through rock formations and the resulting radiation exposure of reference persons. Calculations using Asse II parameters

International Nuclear Information System (INIS)

Kueppers, Christian; Ustohalova, Veronika; Steinhoff, Mathias

2012-01-01

The long-term release of radioactivity into the ground water path cannot be excluded for the radioactive waste repository Asse II. The possible radiological consequences were analyzed using a radio-ecological scenario developed by GRS. A second scenario was developed considering the solubility of radionuclides in salt saturated solutions and retarding/retention effects during the radionuclide transport through the cap rock layers. The modeling of possible radiation exposure was based on the lifestyle habits of reference persons. In Germany the calculation procedure for the prediction of radionuclide release from final repositories is not defined by national standards, the used procedures are based on analogue methods from other radiation protection calculations.

Development of the numerical model for reactive transport of radionuclide and bacteria in the single fractured rock

International Nuclear Information System (INIS)

Kim, Jung Woo; Baik, Min Hoon

2010-12-01

On the aspects of safety case of HLW deep geological disposal system, recently, many researchers in the world have been actively studying about the bacterial effects on the radionuclide transport in the fractured rock. However, the domestic research level related on the area is still insufficient. Therefore, the objective of the research is to introduce the theory and development process of the numerical model, which was newly developed to examine the bacterial effects on the radionuclide transport in the single fractured rock, and to test the model by simulating in some imaginary conditions. From the verification by comparing the simulation results with analytical solution considering only solute transport and rock diffusion, the Pearson's correlation coefficient was greater than 0.99 which demonstrates the accuracy of the model. Since the simulation in the model domain of the single fractured core rock resulted in well-matched mass-balances for all solutes, the robustness and stability of the model could be proved again. Therefore, it is expected that the report can guide the potential model users and can be a referring material for a model developer who is trying to expand and/or update the model

Emission, transport, deposition, and re-suspension of radionuclides from Fukushima Dai-ichi Nuclear Power Plant in the atmosphere - Overview of 2-year investigations in Japan

Science.gov (United States)

Kita, Kazuyuki; Igarashi, Yasuhiro; Yoshida, Naohiro; Nakajima, Teruyuki

2013-04-01

Following a huge earthquake and tsunami in Eastern Japan on 11 March, 2011, the accident in Fukushima Dai-ichi Nuclear Power Plant (FDNPP) occurred to emit a large amount of artificial radionuclides to the environment. Soon after the FDNPP accident, many Japanese researchers, as well as researchers in other countries, started monitoring radionuclides in various environmental fields and/or model calculations to understand extent and magnitude of radioactive pollution. In this presentation, we overview these activities for the atmospheric radionuclides in Japan as followings: 1. Investigations to evaluate radionuclide emissions by explosions at FNDPP in March 2011 and to estimate the respiration dose of the radiation at this stage. 2. Investigations to evaluate atmospheric transport and deposition processes of atmospheric radionuclide to determine the extent of radionuclide pollution. -- Based on results of the regular and urgent monitoring results, as well as the mapping of the distribution of radionuclide s accumulated by the deposition to the ground, restoration of their time-dependent emission rates has been tried, and processes determining atmospheric concentration and deposition to the ground have been investigated by using the model calculations. 3. Monitoring of the atmospheric concentrations of radionuclide after the initial, surge phase of FNDPP accident. 4. Investigations to evaluate re-suspension of radionuclide from the ground, including the soil and the vegetation. -- Intensive monitoring of the atmospheric concentrations and deposition amount of radionuclide after the initial, surge phase of the accident enable us to evaluate emission history from FNDPP, atmospheric transport and deposition processes, chemical and physical characteristics of atmospheric radionuclide especially of radio cesium, and re-suspension processes which has become dominant process to supply radio cesium to the atmosphere recently.

Field verification of advanced transport models of radionuclides in heterogeneous soils

International Nuclear Information System (INIS)

Visser, W.; Meurs, G.A.M.; Weststrate, F.A.

1991-01-01

This report deals with a verification study of advanced transport models of radionuclides in heterogeneous soils. The study reported here is the third phase of a research program carried out by Delft Geotechnics concerning the influence of soil heterogeneities on the migration of radionuclides in the soil and soil-water system. Phases 1 and 2 have been reported earlier in the EC Nuclear Science and technology series (EUR 12111 EN, 1989). The verification study involves the predictive modelling of a field tracer experiment carried out by the British Geological Survey (BGS) at Drigg, Cumbria (UK). Conservative (I 131 , Cl-, H 3 ) as well as non-conservative (Co-EDTA) tracers were used. The inverse modelling shows that micro dispersion may be considered as a soil constant related to grainsize. Micro dispersion shows a slow increase with distance from the source. This increase is caused by mass transfer between adjacent layers of different permeability. Macro dispersion is observed when sampling over a larger interval then permitted by the detail with which the heterogeneity is described in the model. The prediction of the migration of radionuclides through heterogeneous soils is possible. The advection dispersion equation seems to be an adequate description of the migration of conservative tracers. The models based on this equation give comparable results on a small field test scale (3.5 m). The prediction of the migration of adsorbing species is more difficult. The mathematical descriptions seem appropriate, but the heterogeneity in soils seems to create a higher order of uncertainty which can not be described as yet with calculation strategies available at this moment

CRRIS, Health Risk Assessment from Atmospheric Releases of Radionuclides

International Nuclear Information System (INIS)

1999-01-01

1 - Description of program or function: CRRIS consists of eight fully integrated computer codes which calculate environmental transport of atmospheric releases of radionuclides and resulting doses and health risks to individuals or populations. Each code may be used alone for various assessment applications. Because of its modular structure, CRRIS allows assessments to be tailored to the user's needs. Radionuclides are handled by CRRIS either in terms of the released radionuclides or the exposure radionuclides which consist of both the released nuclides and decay products that build up during environmental transport. Atmospheric dispersion calculations are performed by the ANEMOS computer code for distances less than 100 km and the RETADD-II computer code regional-scale distances. Both codes estimate annual-average air concentrations and ground deposition rates by location. SUMIT will translate and scale multiple ANEMOS runs onto a master grid. TERRA reads radionuclide air concentrations and deposition rates to estimate concentrations of radionuclides in food and surface soil. Radiologic decay and ingrowth, soil leaching, and transport through the food chain are included in the calculations. MLSOIL computes an effective radionuclide ground-surface concentration to be used in computing external health effects. The five-layer model of radionuclide transport through soil in MLSOIL provides an alternative to the single-layer model used in TERRA. DFSOIL computes dose factors used in MLSOIL to compute doses from the five soil layers and from the ground surface. ANDROS reads environmental concentrations of radionuclides computed by the other CRRIS codes and produces tables of doses and risks to individuals or populations from atmospheric releases of radionuclides. 2 - Method of solution: SUMIT performs geometric interpolation. TERRA and MLSOIL are terrestrial transport compartment models. DFSOIL computes soil-layer-specific dose factors based on the point-kernel method

Radionuclide fate and effects

International Nuclear Information System (INIS)

Anon.

1983-01-01

The studies reported here deal with the full range of contaminant behavior and fate, from the initial physicochemical factors that govern radionuclide availability in terrestrial and aquatic environments to studies of contaminant transport by biological means. By design, we focus more on the biologically and chemically mediated transport processes and food-chain pathways than on the purely physical forms of contaminant transport, such as transport by wind and water

Development of radionuclide transport model in the ecosystem of brackish lake Obuchi

International Nuclear Information System (INIS)

Ueda, Shinji; Kondo, Kunio; Chikuchi, Yuki; Inaba, Jiro

2003-01-01

The purpose of this study is to develop a computer code for a radionuclide transport model in Lake Obuchi which is adjacent to nuclear fuel cycle facilities including a nuclear spent-fuel reprocessing plant under construction in Rokkasho-mura. The lake is brackish and this fact makes the entry mode of radionuclides into the lake and its ecosystem very characteristic. For the construction of the code, it is important to incorporate the characteristics of the ecosystem as well as the hydraulic movements into the model. In the present study we report the biological parameters related to the transport model obtained from field observations and a laboratory experiment. We also give results from development of an advective-diffusion model. Monthly field observations revealed that 18 to 47 species of phytoplankton, 9 to 20 species of zooplankton and 0 to 21 species of benthos were present in the lake. A marked seasonal change was observed in the dominant species for both planktons. Mean carbon masses of DOC, POC, phytoplankton and zooplankton in the lake were 16 x 10 4 , 5.9 x 10 4 , 3.7 x 10 4 and 0.20 x 10 4 kg-C, respectively. Phytoplanktons of 10 species in 8 genera were isolated and maintained in a bacteria-free medium in the laboratory. Some physiological and metabolic characteristics of the planktons were studied under those conditions. An advective-diffusion model was developed for particles in the lake. Field observations showed that the model could simulate formation and elimination of the water current. (author)

Transport in biosphere of radionuclides released from finally disposed nuclear waste - background information for transport and dose model

International Nuclear Information System (INIS)

Hulmi, R.; Savolainen, I.

1981-07-01

An outline is made about the biosphere transport and dose models employed in the estimation of doses due to releases from finally disposed nuclear waste. The models often divide into two parts; the first one describes the transport of radionuclides in those parts of biosphere where the time scale is large (e.g. soil, sea and sea sediment), the second part of the model describes the transport of nuclides in the systems where the time scale is small (e.g. food chains, plants and animals). The description of biosphere conditions includes remarkable uncertainty due to the complexity of the biosphere and its ecosystems. Therefore studies of scenario type are recommended: some values of parametres describing the conditions are assumed, and the consequences are estimated by using these values. The effect of uncertainty in various factors on the uncertainty of final results should be investigated with the employment of alternative scenarios and parametric sensitivity studies. In addition to the ordinary results, intermediate results should be presented. A proposal for the structure of a transport and dose program based on dynamic linear compartment model is presented and mathematical solution alternatives are studied also

LONG-TERM COLLOID MOBILIZATION AND COLLOID-FACILITATED TRANSPORT OF RADIONUCLIDES IN A SEMI-ARID VADOSE ZONE

Energy Technology Data Exchange (ETDEWEB)

Markus Flury; James B. Harsh; Fred Zhang; Glendon W. Gee; Earl D. Mattson; Peter C. L

2012-08-01

The main purpose of this project was to improve the fundamental mechanistic understanding and quantification of long-term colloid mobilization and colloid-facilitated transport of radionuclides in the vadose zone, with special emphasis on the semi-arid Hanford site. While we focused some of the experiments on hydrogeological and geochemical conditions of the Hanford site, many of our results apply to colloid and colloid-facilitated transport in general. Specific objectives were (1) to determine the mechanisms of colloid mobilization and colloid-facilitated radionuclide transport in undisturbed Hanford sediments under unsaturated flow, (2) to quantify in situ colloid mobilization and colloid-facilitated radionuclidetransport from Hanford sediments under field conditions, and (3) to develop a field-scale conceptual and numerical model for colloid mobilization and transport at the Hanford vadose zone, and use that model to predict long-term colloid and colloid- facilitated radionuclide transport. To achieve these goals and objectives, we have used a combination of experimental, theoretical, and numerical methods at different spatial scales, ranging from microscopic investigationsof single particle attachment and detachment to larger-scale field experiments using outdoor lysimeters at the Hanford site. Microscopic and single particle investigations provided fundamental insight into mechanisms of colloid interactions with the air-water interface. We could show that a moving air water interface (such as a moving water front during infiltration and drainage) is very effective in removing and mobilizing particles from a stationary surface. We further demonstrated that it is particularly the advancing air-water interface which is mainly responsible for colloid mobilization. Forces acting on the colloids calculated from theory corroborated our experimental results, and confirm that the detachment forces (surface tension forces) during the advancing air-water interface

Flow modelling and radionuclide transport research and development in saturated and unsaturated soils

International Nuclear Information System (INIS)

Carvalho Filho, Carlos Alberto de; Branco, Otavio Eurico de Aquino; Loureiro, Celso de Oliveira

1996-01-01

The Engenho Nogueira Hydrogeological Project, PROHBEN, was idealized with the goal of implementing an Experimental Hydrogeological basin within its limits, in order to permit the development of hydrogeological studies and techniques, mainly in the modeling of flow and transport of contaminants (radionuclides) in the saturated and unsaturated porous media. The PROHBEN is located in Belo Horizonte, Minas Gerais, amounting a 5 km 2 area. The local porous-granular, heterogeneous and anisotropic, water-table aquifer reaches 40 meters of thickness, and is compound mainly by alluvial deposits and alteration rocks products, with a sandy texture. The flow and transport modeling are being done using the Modflow and MT3D codes. Three master degree researches are being done in the PROHBEN area and one expects is that more researchers come to use this experimental site. (author)

CRRIS: a methodology for assessing the impact of airborne radionuclide releases

International Nuclear Information System (INIS)

Baes, C.F. III; Miller, C.W.

1983-01-01

The Computerized Radiological Risk Investigation System (CRRIS) consists of six fully integrated computer codes which calculate environmental transport and resulting doses and risks to individuals or populations exposed to atmospheric radionuclide releases. The individual codes may be used alone for various assessment applications or may be run as a system. This presentation provides an overview and introduction to this system of computer codes and their use in conducting nuclear assessments. Radionuclides are handled by CRRIS either in terms of the released radionuclides or in terms of exposure radionuclides which consist of both the released nuclides and all (or a subset of) the decay daughters that grow in during environmental transport. The capability of CRRIS to handle radionuclide chains is accomplished through PRIMUS which serves as a preprocessor by accessing a library of radionuclide decay data and sets up matricies of decay constants which are used by the other CRRIS codes in all calculations involving transport and decay. PRIMUS may also be run independently by the user to define the decay chains, radionuclide decay constants, and branching ratios

Transport of radionuclides by bentonite and silica colloids in a GR-3 synthetic groundwater-interim report

International Nuclear Information System (INIS)

Ames, L.L.; McGarrah, J.E.; Walker, B.A.

1983-08-01

Radionuclide distributions in groundwater-colloid-basalt systems were measured using GR-3 groundwater and crushed Umtanum basalt at 60 degree C. The objective was to estimate the potential for radionuclide transport from a nuclear waste repository in basalt by colloids suspended in groundwater. Three colloids were studied -- a bentonite colloid representing a potential component of packing or backfill materials in the repository, and two hydrated silica colloids which might represent those generated from a glass waste form. The radioelements studied included isotopes of neptunium, uranium, selenium, technetium, and radium. Measurements of radionuclide distributions in experiments with the bentonite colloid showed that uranium was sorbed strongly on the colloid (under both oxidizing and reducing conditions) but was readily transferred to basalt when it was added to the system. Sorption of neptunium, technetium, and selenium on the colloid was greatly enhanced by using reducing conditions. Only small amounts of neptunium and technetium were transferred to the basalt under reducing conditions, but most of the selenium was readily transferred under these conditions

Mathematical modelling of radionuclide transport through fractured rock using numerical inversion of Laplace transforms: applications to INTRACOIN Level 3

International Nuclear Information System (INIS)

Hodgkinson, D.P.; Lever, D.A.; England, T.H.

1984-01-01

A model for the transport of radionuclides through fractured rock has been developed and used to study a problem which forms part of Level 3 of the INTRACOIN project (the international exercise in which the results from various radionuclide-migration computer programs are compared). The model includes the effects of 1-D advection, dispersion, kinetic and/or equilibrium surface sorption, diffusion into the rock matrix with equilibrium bulk sorption and radioactive decay, and incorporates flexible input and output boundary conditions. It is evaluated by numerically inverting the analytical solution to the Laplace-transformed transport equations. Matrix diffusion was found to be the most important retardation mechanism for Np based on data reflecting the conditions at the Finnsjeeo site in east central Sweden. However, improved data and field testing are required to make the predictions of such models more reliable. (author)

SATURATED ZONE FLOW AND TRANSPORT MODEL ABSTRACTION

International Nuclear Information System (INIS)

B.W. ARNOLD

2004-01-01

The purpose of the saturated zone (SZ) flow and transport model abstraction task is to provide radionuclide-transport simulation results for use in the total system performance assessment (TSPA) for license application (LA) calculations. This task includes assessment of uncertainty in parameters that pertain to both groundwater flow and radionuclide transport in the models used for this purpose. This model report documents the following: (1) The SZ transport abstraction model, which consists of a set of radionuclide breakthrough curves at the accessible environment for use in the TSPA-LA simulations of radionuclide releases into the biosphere. These radionuclide breakthrough curves contain information on radionuclide-transport times through the SZ. (2) The SZ one-dimensional (I-D) transport model, which is incorporated in the TSPA-LA model to simulate the transport, decay, and ingrowth of radionuclide decay chains in the SZ. (3) The analysis of uncertainty in groundwater-flow and radionuclide-transport input parameters for the SZ transport abstraction model and the SZ 1-D transport model. (4) The analysis of the background concentration of alpha-emitting species in the groundwater of the SZ

PRESTO low-level waste transport and risk assessment code

International Nuclear Information System (INIS)

Little, C.A.; Fields, D.E.; McDowell-Boyer, L.M.; Emerson, C.J.

1981-01-01

PRESTO (Prediction of Radiation Effects from Shallow Trench Operations) is a computer code developed under US Environmental Protection Agency (EPA) funding to evaluate possible health effects from shallow land burial trenches. The model is intended to be generic and to assess radionuclide transport, ensuing exposure, and health impact to a static local population for a 1000-y period following the end of burial operations. Human exposure scenarios considered by the model include normal releases (including leaching and operational spillage), human intrusion, and site farming or reclamation. Pathways and processes of transit from the trench to an individual or population inlude: groundwater transport, overland flow, erosion, surface water dilution, resuspension, atmospheric transport, deposition, inhalation, and ingestion of contaminated beef, milk, crops, and water. Both population doses and individual doses are calculated as well as doses to the intruder and farmer. Cumulative health effects in terms of deaths from cancer are calculated for the population over the thousand-year period using a life-table approach. Data bases are being developed for three extant shallow land burial sites: Barnwell, South Carolina; Beatty, Nevada; and West Valley, New York

Research summary: characterization of radionuclide and moisture movement through arid region sediments

International Nuclear Information System (INIS)

Gee, G.W.; Jones, T.L.; Rai, D.

1981-09-01

This project has the task of understanding the movement of moisture and radionuclides under arid region conditions. This understanding will be used to maximize the isolation of low level waste from the environment. Specific objectives include: field monitoring of moisture and radionuclide transport at an arid region site; assessment of the interaction of radionuclides with unsaturated soils in arid regions; evaluation of radionuclide transport in unsaturated soils by appropriate mathematical models; and assessment of the importance of upward migration of radionuclides by evaporation and diffusion processes. The Burial Waste Test Facility (BWTF) located near Richland, Washington, on the Department of Energy (DOE) Hanford Site has been monitored for water content and radionuclide transport for the past two years. Tritium movement has been observed to depths of 7.6 m in both irrigated and nonirrigated lysimeters. Laboratory tests were conducted to determine how leachate from uranium tailings interacts with geologic materials. Acid leach tailings and tailings solution and geologic materials typical of mill site tailing pits were physically and chemically characterized. Investigation was made of the sorption characteristics of heavy metals and radionuclides on the geologic materials under low and neutral pH conditions. From solubility tests conducted at Pacific Northwest Laboratory, thermodynamic considerations predicted that for the Eh-pH range of natural aqueous environment, the dominant species of Pu is likely to be Pu(V) in relatively oxidizing environments and Pu(III) in reducing environments. Radionuclide transport through unsaturated media was investigated by using two solute transport models to describe the transport of tritium and strontium-85 in laboratory columns. A new approach was used to analyze radon emissions from uranium mill tailings

Conceptual and numerical modelling of radionuclide transport in near-surface systems at Forsmark. SR-Site Biosphere

International Nuclear Information System (INIS)

Pique, Angels; Grandia, Fidel; Sena, Clara; Arcos, David; Molinero, Jorge; Duro, Lara; Bruno, Jordi

2010-11-01

In the framework of the SR-Site safety assessment, a conceptual and numerical modelling of radionuclide reactive transport in near-surface systems (including till and clay systems) at Forsmark has been carried out. The objective was to evaluate the retention capacity of the near-surface systems, composed of Quaternary deposits, which would be the last natural barrier for an eventual radionuclide release from the deep repository prior to reaching the biosphere. The studied radionuclides are 14 C, 129 I, 36 Cl, 94 Nb, 59 Ni, 93 Mo, 79 Se, 99 Tc, 230 Th, 90 Sr, 226 Ra, 135 Cs and U. Conceptual description and numerical simulations of radionuclide reactive transport show that cation exchange and surface complexation on illite are active processes for the retention of several radionuclides (U, Th, Ni, Cs, Sr, Ra). Surface complexation on iron hydroxide is an active process in the till system, able to effectively retain U and Ni. Another retention process of importance is the incorporation of the radionuclides into mineral phases, either by the precipitation of pure phases or solid solutions. Quantitative modelling has been useful to illustrate the incorporation of C and Sr in the carbonate solid solution in the considered model domains (till and clay), as well as the precipitation of uraninite in the clay sediments and the precipitation of native selenium and radiobarite in the till. Other mineral phases that could, a priori, retain U, Se, Nb and Tc do not precipitate in the simulations, either due to the pH-Eh conditions and/or because the dissolved concentration of the element is not high enough under the considered simulation conditions. It is important to keep in mind that changes in these parameters and in the boundary conditions could modify the predicted behaviour of these elements. The radionuclides that are most significantly retarded are Th, Ni and Cs, mainly through sorption onto illite. Therefore, if the amount of illite (or available sorption sites

Conceptual and numerical modelling of radionuclide transport in near-surface systems at Forsmark. SR-Site Biosphere

Energy Technology Data Exchange (ETDEWEB)

Pique, Angels; Grandia, Fidel; Sena, Clara; Arcos, David; Molinero, Jorge; Duro, Lara; Bruno, Jordi (Amphos21 Consulting S.L., Barcelona (Spain))

2010-11-15

In the framework of the SR-Site safety assessment, a conceptual and numerical modelling of radionuclide reactive transport in near-surface systems (including till and clay systems) at Forsmark has been carried out. The objective was to evaluate the retention capacity of the near-surface systems, composed of Quaternary deposits, which would be the last natural barrier for an eventual radionuclide release from the deep repository prior to reaching the biosphere. The studied radionuclides are 14C, 129I, 36Cl, 94Nb, 59Ni, 93Mo, 79Se, 99Tc, 230Th, 90Sr, 226Ra, 135Cs and U. Conceptual description and numerical simulations of radionuclide reactive transport show that cation exchange and surface complexation on illite are active processes for the retention of several radionuclides (U, Th, Ni, Cs, Sr, Ra). Surface complexation on iron hydroxide is an active process in the till system, able to effectively retain U and Ni. Another retention process of importance is the incorporation of the radionuclides into mineral phases, either by the precipitation of pure phases or solid solutions. Quantitative modelling has been useful to illustrate the incorporation of C and Sr in the carbonate solid solution in the considered model domains (till and clay), as well as the precipitation of uraninite in the clay sediments and the precipitation of native selenium and radiobarite in the till. Other mineral phases that could, a priori, retain U, Se, Nb and Tc do not precipitate in the simulations, either due to the pH-Eh conditions and/or because the dissolved concentration of the element is not high enough under the considered simulation conditions. It is important to keep in mind that changes in these parameters and in the boundary conditions could modify the predicted behaviour of these elements. The radionuclides that are most significantly retarded are Th, Ni and Cs, mainly through sorption onto illite. Therefore, if the amount of illite (or available sorption sites) decreases, the

The Grimsel radionuclide migration experiment - a contribution to raising confidence in the validity of solute transport models used in performance assessment

International Nuclear Information System (INIS)

Frick, U.

1995-01-01

The safety assessment of radioactive waste repositories is to provide confidence that the predictive models utilized are applicable for the specific repository systems. Nagra has carried out radionuclide migration experiments at the Grimsel underground test site (Switzerland) for testing of currently used methodologies, data bases, conceptual approaches and codes for modeling radionuclide transport through fractured host rocks. Specific objectives included: identification of the relevant transport processes, to test the extrapolation of laboratory sorption data to field conditions, and to demonstrate the applicability of currently used methodology for conceptualizing or building realistic transport models. Field tests and transport modeling work are complemented by an extensive laboratory program. The field experimental activities focused predominantly on establishing appropriate conditions for identifying relevant transport mechanisms on the scale of a few meters, aiming at full recovery of injected tracers, simple geometry and long-term stability of induced dipole flow fields. A relatively simple homogeneous, dual-porosity advection/diffusion model was built with input from a state of the art petrographic characterisation of the water conducting feature. It was possible to calibrate the model from conservative tracer breakthrough curves. (J.S.). 21 refs., 14 figs., 4 tabs

TERRA: a computer code for simulating the transport of environmentally released radionuclides through agriculture

International Nuclear Information System (INIS)

Baes, C.F. III; Sharp, R.D.; Sjoreen, A.L.; Hermann, O.W.

1984-11-01

TERRA is a computer code which calculates concentrations of radionuclides and ingrowing daughters in surface and root-zone soil, produce and feed, beef, and milk from a given deposition rate at any location in the conterminous United States. The code is fully integrated with seven other computer codes which together comprise a Computerized Radiological Risk Investigation System, CRRIS. Output from either the long range (> 100 km) atmospheric dispersion code RETADD-II or the short range (<80 km) atmospheric dispersion code ANEMOS, in the form of radionuclide air concentrations and ground deposition rates by downwind location, serves as input to TERRA. User-defined deposition rates and air concentrations may also be provided as input to TERRA through use of the PRIMUS computer code. The environmental concentrations of radionuclides predicted by TERRA serve as input to the ANDROS computer code which calculates population and individual intakes, exposures, doses, and risks. TERRA incorporates models to calculate uptake from soil and atmospheric deposition on four groups of produce for human consumption and four groups of livestock feeds. During the environmental transport simulation, intermediate calculations of interception fraction for leafy vegetables, produce directly exposed to atmospherically depositing material, pasture, hay, and silage are made based on location-specific estimates of standing crop biomass. Pasture productivity is estimated by a model which considers the number and types of cattle and sheep, pasture area, and annual production of other forages (hay and silage) at a given location. Calculations are made of the fraction of grain imported from outside the assessment area. TERRA output includes the above calculations and estimated radionuclide concentrations in plant produce, milk, and a beef composite by location

TERRA: a computer code for simulating the transport of environmentally released radionuclides through agriculture

Energy Technology Data Exchange (ETDEWEB)

Baes, C.F. III; Sharp, R.D.; Sjoreen, A.L.; Hermann, O.W.

1984-11-01

TERRA is a computer code which calculates concentrations of radionuclides and ingrowing daughters in surface and root-zone soil, produce and feed, beef, and milk from a given deposition rate at any location in the conterminous United States. The code is fully integrated with seven other computer codes which together comprise a Computerized Radiological Risk Investigation System, CRRIS. Output from either the long range (> 100 km) atmospheric dispersion code RETADD-II or the short range (<80 km) atmospheric dispersion code ANEMOS, in the form of radionuclide air concentrations and ground deposition rates by downwind location, serves as input to TERRA. User-defined deposition rates and air concentrations may also be provided as input to TERRA through use of the PRIMUS computer code. The environmental concentrations of radionuclides predicted by TERRA serve as input to the ANDROS computer code which calculates population and individual intakes, exposures, doses, and risks. TERRA incorporates models to calculate uptake from soil and atmospheric deposition on four groups of produce for human consumption and four groups of livestock feeds. During the environmental transport simulation, intermediate calculations of interception fraction for leafy vegetables, produce directly exposed to atmospherically depositing material, pasture, hay, and silage are made based on location-specific estimates of standing crop biomass. Pasture productivity is estimated by a model which considers the number and types of cattle and sheep, pasture area, and annual production of other forages (hay and silage) at a given location. Calculations are made of the fraction of grain imported from outside the assessment area. TERRA output includes the above calculations and estimated radionuclide concentrations in plant produce, milk, and a beef composite by location.

Sediment and radionuclide transport in rivers. Summary report, field sampling program for Cattaraugus and Buttermilk Creeks, New York

International Nuclear Information System (INIS)

Walters, W.H.; Ecker, R.M.; Onishi, Y.

1982-11-01

A three-phase field sampling program was conducted on the Buttermilk-Cattaraugus Creek system to investigate the transport of radionuclides in surface waters as part of a continuing program to provide data for application and verification of Pacific Northwest Laboratory's (PNL) sediment and radionuclide transport model, SERATRA. Phase 1 of the sampling program was conducted during November and December 1977; Phase 2 during September 1978; and Phase 3 during April 1979. Bed sediment, suspended sediment, and water samples were collected over a 45-mile reach of the creek system. Bed sediment samples were also collected at the mouth of Cattaraugus Creek in Lake Erie. A fourth sampling trip was conducted during May 1980 to obtain supplementary channel geometry data and flood plain sediment samples. Radiological analysis of these samples included gamma ray spectrometry analysis, and radiochemical separation and analysis of Sr-90, Pu-238, Pu-239,240, Am-241 and Cm-244. Tritium analysis was also performed on water samples. Based on the evaluation of radionuclide levels in Cattaraugus and Buttermilk Creeks, the Nuclear Fuel Services facility at West Valley, New York, may be the source of Cs-137, Sr-90, CS-134, Co-60, Pu-238, Pu-239,240, Am-241, Cm-244 and tritium found in the bed sediment, suspended sediment and water of Buttermilk and Cattaraugus Creeks

FTRANS, Radionuclide Flow in Groundwater and Fractured Rock

International Nuclear Information System (INIS)

Huyakorn, P.; Golis, M.J.

1987-01-01

1 - Description of program or function: FTRANS (Fractured flow and Transport of Radionuclides) is a two-dimensional finite-element code designed to simulate ground-water flow and transport of radioactive nuclides in a fractured porous return medium. FTRANS takes into account fluid interactions between the fractures and porous matrix blocks, advective-dispersive transport in the fractures and diffusion in the porous matrix blocks, and chain reactions of radionuclide components. It has the capability to model the fractured system using either the dual-porosity or the discrete- fracture modeling approach or a combination of both. FTRANS can be used to perform two-dimensional near-field or far-field predictive analyses of ground-water flow and to perform risk assessments of radionuclide transport from nuclear waste repository subsystems to the biosphere. 2 - Restrictions on the complexity of the problem: Although FTRANS does cannot account for deformation processes which can affect the flow capacity and velocity field

Status of subseabed repository design concepts and radionuclide

International Nuclear Information System (INIS)

Brush, L.H.

1980-01-01

Various projects underway in support of the marine disposal of radioactive wastes are described. These include: geochemical studies on sediments; canister-related research and development activities; radionuclide transport studies through smectitic sediments; seawater-sediment interactions under near-field conditions; effects of a radiation field on high temperature, seawater-sediment interactions; sorption of fission products and actinides by deep-sea sediments under far-field (below 100 0 C) conditions; sorption experiments using column diffusion; development of a computer code, IONMIG, to model the migration of radionuclides through undisturbed deep-sea sediments; and planning for a field test of the laboratory measurements and computer models of radionuclide transport

Analysis of NSPP experiment with ART code for analyzing transport behavior of Aerosol and radionuclides

International Nuclear Information System (INIS)

Ishigami, Tsutomu; Kobayashi, Kensuke; Kajimoto, Mitsuhiro.

1989-01-01

The ART code calculates transport behavior of aerosols and radionuclides during core meltdown accidents in the light water reactors. Since aerosols play an important role in carrying fission products from the core region to the environment, the ART code includes detailed models of aerosol behavior. Aerosols including several radionuclides are classified into many groups according to the aerosol mass. The models of aerosol behavior include agglomeration processes caused by Brownian motion, aerosol settling velocity difference and turbulent flow, and natural deposition processes due to diffusion, thermophoresis, diffusiophoresis, gravitational settling and forced convection. In order to examine validity of the ART models, the NSPP aerosol experiment was analyzed. The ART calculated results showed good agreement with the experimental data. It was ascertained that aerosol growth due to agglomeration, gravitational settling, thermophoresis in an air atmosphere, and diffusiophoresis in an air-steam atmosphere were important physical phenomena in the aerosol behavior. (author)

Investigating radionuclide bearing suspended sediment transport mechanisms in the Ribble estuary using airborne remote sensing

International Nuclear Information System (INIS)

Atkin, P.A.

2000-10-01

BNFL Sellafield has been authorised to discharge radionuclides to the Irish Sea since 1952. In the aquatic environment the radionuclides are adsorbed by sediments and are thus redistributed by sediment transport mechanisms. This sediment is known to accumulate in the estuaries of the Irish Sea. BNFL Springfields is also licensed to discharge isotopically different radionuclides directly to the Ribble estuary. Thus there is a need to understand the sediment dynamics of the Ribble estuary in order to understand the fate of these radionuclides within the Ribble estuary. Estuaries are highly dynamic environments that are difficult to monitor using the conventional sampling techniques. However, remote sensing provides a potentially powerful tool for monitoring the hydrodynamics of the estuarine environment by providing data that are both spatially and temporally representative. This research develops a methodology for mapping suspended sediment concentration (SSC) in the Ribble estuary using airborne remote sensing. The first hypothesis, that there is a relationship between SSC and 137 Cs concentration is proven in-situ (R 2 =0.94), thus remotely sensed SSC can act as a surrogate for 137 Cs concentration. Initial in-situ characterisation of the suspended sediments was investigated to identify spatial and temporal variability in grain size distributions and reflectance characteristics for the Ribble estuary. Laboratory experiments were then performed to clearly define the SSC reflectance relationship, identify the optimum CASI wavelengths for quantifying SSC and to demonstrate the effects on reflectance of the environmental variables of salinity and clay content. Images were corrected for variation in solar elevation and angle to give a ground truth calibration for SSC, with an R 2 =0.76. The remaining scatter in this relationship was attributed to the differences in spatial and temporal representation between sampling techniques and remote sensing. The second hypothesis

MARFA user's manual: Migration analysis of radionuclides in the far field

International Nuclear Information System (INIS)

Painter, S.; Mancillas, J.

2013-12-01

The computer code Migration Analysis of Radionuclides in the Far Field (MARFA) uses a particle-based Monte Carlo method to simulate the transport of radionuclides in a sparsely fractured geological medium. The algorithm uses non-interacting particles to represent packets of radionuclide mass. These particles are moved through the system according to rules that mimic the underlying physical transport and retention processes. The physical processes represented in MARFA include advection, longitudinal dispersion, Fickian diffusion into an infinite or finite rock matrix, equilibrium sorption, decay, and in-growth. Because the algorithm uses non-interacting particles, the transport and retention processes are limited to those that depend linearly on radionuclide concentration. Multiple non-branching decay chains of arbitrary length are supported, as is full heterogeneity in the transport and retention properties. Two variants of the code are provided. These two versions differ in how particles are routed through the computational domain. In MARFA 3.2.3, transport is assumed to occur along a set of trajectories or pathways that originate at radionuclide source locations. The trajectories are intended to represent the movement of hypothetical, advectively transported groundwater tracers and are typically calculated by pathline tracing in a discrete fracture network flow code. The groundwater speed and retention properties along each pathway may change in time, but the pathway trajectories are fixed. MARFA 3.3.1 allows the transport effects of changing flow directions to be represented by abandoning the fixed pathways and performing node routing within MARFA. (orig.)

Modelling of Radionuclide Transport by Groundwater Motion in Fractured Bedrock for Performance Assessment Purposes

International Nuclear Information System (INIS)

Woerman, Anders; Shulan Xu

2003-10-01

Field data of physical properties in heterogeneous crystalline bedrock, like fracture zones, fracture connectivity, matrix porosity and fracture aperture, is associated with uncertainty that can have a significant impact on the analysis of solute transport in fractured rock. The purpose of this study is to develop a performance assessment (PA) model for analyses of radionuclide transport in the geosphere, in which the model takes into account both the effect of heterogeneities of hydrological and geochemical rock properties. By using a travel time description of radionuclide transport in rock fractures, we decompose the transport problem into a one-dimensional mass transfer problem along a distribution of transport pathways and a multi-dimensional flow problem in the fractured bedrock. The hydraulic/flow problem is solved based on a statistical discrete-fracture model (DFM) that represents the network of fractures around the repository and in the surrounding geosphere. A Monte Carlo technique reflects the fact that the representation of the fracture network is uncertain. If the flow residence time PDF exhibits multiple peaks or in another way shows a more erratic hydraulic response on the network scale, the three-dimensional travel time approach is superior to a one-dimensional transport modeling. Examples taken from SITE 94, a study performed by the Swedish Nuclear Power Inspectorate, showed that such cases can be found in safety assessments based on site data. The solute transport is formulated based on partial, differential equations and perturbations (random spatial variability in bedrock properties) are introduced in the coefficients to reflect an uncertainty of the exact appearance of the bedrock associated with the discrete data collection. The combined approach for water flow and solute transport, thereby, recognises an uncertainty in our knowledge in both 1) bedrock properties along individual pathways and 2) the distribution of pathways. Solutions to the

Radionuclide and colloid transport in the Culebra Dolomite and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant

Energy Technology Data Exchange (ETDEWEB)

RAMSEY, JAMES L.; BLAINE,R.; GARNER,J.W.; HELTON,JON CRAIG; JOHNSON,J.D.; SMITH,L.N.; WALLACE,M.

2000-05-22

The following topics related to radionuclide and colloid transport in the Culebra Dolomite in the 1996 performance assessment for the Waste Isolation Pilot Plant (WIPP) are presented: (1) mathematical description of models, (2) uncertainty and sensitivity analysis results arising from subjective (i.e., epistemic) uncertainty for individual releases, and (3) construction of complementary cumulative distribution functions (CCDFs) arising from stochastic (i.e., aleatory) uncertainty. The presented results indicate that radionuclide and colloid transport in the Culebra Dolomite does not constitute a serious threat to the effectiveness of the WIPP as a disposal facility for transuranic waste. Even when the effects of uncertain analysis inputs are taken into account, no radionuclide transport to the boundary with the accessible environment was observed; thus the associated CCDFs for comparison with the boundary line specified in the US Environmental Protection Agency's standard for the geologic disposal of radioactive waste (40 CFR 191, 40 CFR 194) are degenerate in the sense of having a probability of zero of exceeding a release of zero.

Field test facility for monitoring water/radionuclide transport through partially saturated geologic media: design, construction, and preliminary description

International Nuclear Information System (INIS)

Phillips, S.J.; Campbell, A.C.; Campbell, M.D.; Gee, G.W.; Hoober, H.H.; Schwarzmiller, K.O.

1979-11-01

Shallow land burial has been a common practice for disposing radioactive waste materials since the beginning of plutonium production operations. Accurate monitoring of radionuclide transport and factors causing transport within the burial sites is essential to minimizing risks associated with disposal. However, monitoring has not always been adequate. Consequently, the Department of Energy (DOE) has begun a program aimed at better assuring and evaluating containment of radioactive wastes at shallow land burial sites. This program includes a technological base for monitoring transport. As part of the DOE program, Pacific Northwest Laboratory (PNL) is developing geohydrologic monitoring systems to evaluate burial sites located in arid regions. For this project, a field test facility was designed and constructed to assess monitoring systems for near-surface disposal of radioactive waste and to provide information for evaluating site containment performance. The facility is an integrated network of monitoring devices and data collection instruments. This facility is used to measure water and radionuclide migration under field conditions typical of arid regions. Monitoring systems were developed to allow for measurement of both mass and energy balance. Work on the facility is ongoing. Continuing work includes emplacement of prototype monitoring instruments, data collection, and data synthesis. At least 2 years of field data are needed to fully evaluate monitoring information

La sociedad de ensueño del turismo

Directory of Open Access Journals (Sweden)

Ruth Arroyo

2011-11-01

Full Text Available Este artículo proclama el nacimiento de una nueva sociedad denominada la sociedad de ensueño. Se presenta como un tema fascinante sobre la demanda futura de bienes y servicios, que predice que la sociedad actual, basada en la información, se convertirá en una sociedad que valora las historias detrás de los productos y servicios. Estas historias se construyen a partir de la necesidad de riqueza emocional, que la riqueza material ha convertido en algo común. La demanda de productos, a su vez aumentará la demanda de contadores de historias imaginativas que artísticamente pueden dirigir las emociones de los consumidores de una diversificada cultura global, donde imaginar, crear, divertir y fascinar puede resultar un duro trabajo para nuestros conceptos actuales. El resultado de la sociedad de ensueño es que los consumidores no compran productos sino estilos de vida e “historias”, experiencias, emociones y elementos que transmiten un sentido o un significado. En el artículo se menciona cómo los negocios de la industria turística se están transformando, y también se habla de los cambios en otros ámbitos de la sociedad como: el lugar de trabajo, la casa, las relaciones entre las personas y las naciones. Este tema es recomendado para el sector académico y empresarial.

Activation analysis with neutron generators using short-lived radionuclides

International Nuclear Information System (INIS)

Salma, I.

1993-01-01

The short half-life involves a number of important differences in production, transportation and measurement of radionuclides, and in counting statistics as compared with those in traditional activation analysis. Experiments were performed to investigate the analytical possibilities and prospective utilization of short-lived radionuclides produced by 14-MeV neutron irradiation. A rapid pneumatic transfer system for use with neutron generators was installed and applied for detecting radionuclides with a half-life from 300 ms to 30 s. The transport time for samples with a total mass of 1-4 g is between 130 and 160 ms for pressurized air of 0.1-0.4 MPa. 11 elements were studied by the conventional activation method using both a typical pneumatic transport system (run time 3 s) and the fast pneumatic transport facility. The effect of the cyclic activation technique on the elemental sensitivities was also investigated. (orig.)

Acceptable-doses exceeding in radionuclides transport

International Nuclear Information System (INIS)

Delabarre, P.

2006-01-01

Without any foregoing signal, the 12-gliding month dose in an employee of a radionuclides transporting firm raised to 44,30 mSv (over the double of the ICRP recommended yearly maximum of 20 mSv). Apart from immediate prohibition of any further professional exposure to ionising radiation for the employee concerned, and an inquiry for possible explanations concerning as well the employer as the employee, an in-depth investigation of the employees previous records took place. Except from the sudden rise, the investigation showed that the personal dosimeter was mostly presented for analysis weeks, even months, too late, what made any immediate action from occupational health and radioprotection side difficult and anyhow far too late. Investigation of the records of the other 30 employees showed that 1) mostly the dosimeters were not presented on the assumed date for analysis, but months to (sometimes) nearly one year late behind schedule 2) for the same job in the same period, registered doses varied from naught to over 8,00 mSv, depending on the employee 3) several employees had a 12-gliding months dose of over 10,00 mSv, even over 15,00 mSv During discussion with employee, employer, occupational physician and an agent of the qualified organisation for dosimeter analysis, the employer was anything but cooperative; the employee also was rather reluctant to answer questions, and given possible causes could not be corroborated. In an attempt to clarify the multiple problems, the Governmental Agency for Nuclear Control was involved, which imposed in a first time a( not very stringent, rather indulgent) action plan. Meanwhile, a written comment on the monthly dosimeter analyses was sent from as well the occupational physician as the analytical firm to the employer and to the concerned employees if a 12-gliding months dose exceeding 10 mSv was determined, without any reaction neither from the employer nor the employees. At the moment of the abstract submission (sept 05

Transuranic radionuclides dispersed into the aquatic environment, a bibliography

Energy Technology Data Exchange (ETDEWEB)

Noshkin, V.E.; Stoker, A.C.; Wong, Kai M. [and others

1994-04-01

The purpose of this project was to compile a bibliography of references containing environmental transuranic radionuclide data. Our intent was to identify those parameters affecting transuranic radionuclide transport that may be generic and those that may be dependent on chemical form and/or environmental conditions (i.e., site specific) in terrestrial, aquatic and atmospheric environments An understanding of the unique characteristics and similarities between source terms and environmental conditions relative to transuranic radionuclide transport and cycling will provide the ability to assess and predict the long term impact on man and the environment. An additional goal of our literature review, was to extract the ranges of environmental transuranic radionuclide data from the identified references for inclusion in a data base. Related to source term, these ranges of data can be used to calculate the dose to man from the radionuclides, and to perform uncertainty analyses on these dose assessments. On the basis of our reviews, we have arbitrarily outlined five general source terms. These are fallout, fuel cycle waste, accidents, disposal sites and resuspension. Resuspension of the transuranic radionuclides is a unique source term, in that the radionuclides can originate from any of the other source terms. If these transuranic radionuclides become resuspended into the air, they then become important as a source of inhaled radionuclides.

Low-level waste shallow burial assessment code

International Nuclear Information System (INIS)

Fields, D.E.; Little, C.A.; Emerson, C.J.

1981-01-01

PRESTO (Prediction of Radiation Exposures from Shallow Trench Operationns) is a computer code developed under United States Environmental Protection Agency funding to evaluate possible health effects from radionuclide releases from shallow, radioctive-waste disposal trenches and from areas contaminated with operational spillage. The model is intended to predict radionuclide transport and the ensuing exposure and health impact to a stable, local population for a 1000-year period following closure of the burial grounds. Several classes of submodels are used in PRESTO to represent scheduled events, unit system responses, and risk evaluation processes. The code is modular to permit future expansion and refinement. Near-surface transport mechanisms considered in the PRESTO code are cap failure, cap erosion, farming or reclamation practices, human intrusion, chemical exchange within an active surface soil layer, contamination from trench overflow, and dilution by surface streams. Subsurface processes include infiltration and drainage into the trench, the ensuing solubilization of radionuclides, and chemical exchange between trench water and buried solids. Mechanisms leading to contaminated outflow include trench overflow and downwad vertical percolation. If the latter outflow reaches an aquifer, radiological exposure from irrigation or domestic consumption is considered. Airborne exposure terms are evaluated using the Gaussian plume atmospheric transport formulation as implemented by Fields and Miller

Solute transport in fractured rock - applications to radionuclide waste repositories

International Nuclear Information System (INIS)

Neretnieks, I.

1990-12-01

Flow and solute transport in fractured rocks has been intensively studied in the last decade. The increased interest is mainly due to the plans in many countries to site repositories for high level nuclear waste in deep geologic formations. All investigated crystalline rocks have been found to be fractured and most of the water flows in the fractures and fracture zones. The water transports dissolved species and radionuclides. It is thus of interest to be able to understand and to do predictive modelling of the flowrate of water, the flowpaths and the residence times of the water and of the nuclides. The dissolved species including the nuclides will interact with the surrounding rock in different ways and will in many cases be strongly retarded relative to the water velocity. Ionic species may be ion exchanged or sorbed in the mineral surfaces. Charges and neutral species may diffuse into the stagnant waters in the rock matrix and thus be withdrawn from the mobile water. These effects will be strongly dependent on how much rock surface is in contact with the flowing water. It has been found in a set of field experiments and by other observations that not all fractures conduct water. Furthermore it is found that conductive fractures only conduct the water in a small part of the fracture in what is called channels or preferential flowpaths. This report summarizes the present concepts of water flow and solute transport in fractured rocks. The data needs for predictive modelling are discussed and both field and laboratory measurement which have been used to obtain data are described. Several large scale field experiments which have been specially designed to study flow and tracer transport in crystalline rocks are described. In many of the field experients new techniques have been developed and used. (81 refs.) (author)

Radionuclide migration in the unsaturated zone with a variable hydrology

International Nuclear Information System (INIS)

Elert, M.; Collin, M.; Andersson, Birgitta; Lindgren, M.

1990-01-01

Radionuclide transport from contaminated ground water to the root zone of a soil has been modelled considering a variable hydrology. Hydrological calculations have been coupled with radionuclide transport calculations in order to study the influence of variations in flow rate and saturation, dispersion, and sorption. For non-sorbing radionuclides important seasonal variations in the root zone concentration were found. The dispersivity parameter proved to be very important for both sorbing and non-sorbing nuclides. In addition, some comparison calculations were made with a simple steady-state compartment model. (au)

Estimates of potential radionuclide migration at the Bullion site

International Nuclear Information System (INIS)

Brikowski, T.H.

1992-04-01

The Bullion site in Area 20 of the Nevada Test Site has been selected for an intensive study of the hydrologic consequences of underground testing, including subsequent radionuclide migration. The bulk of the chimney and cavity lie in zeolitized tuffs of low hydraulic conductivity, while the base of the cavity may extend downward into more conductive rhyolite flows. A mathematical analog to the Bullion setting is used here to estimate expected radionuclide migration rates and concentrations. Because of a lack of hydrologic data at the site, two contrasting scenarios are considered. The first is downward-transport, in which downward hydraulic gradients flush chimney contents into the conductive underlying units, enhancing migration. The other is upward-transport, in which upward gradients tend to drive chimney contents into the low-conductivity zeolitized tuffs, discouraging migration. In the downward-transport scenario, radionuclide travel times and concentrations are predicted to be similar to those encountered at Cheshire, requiring approximately 10 years to reach a proposed well 300 m downgradient. The upward transport scenario yields predicted travel times on the order of 2,000 years to the downgradient well. The most likely scenario is a combination of these results, with vertical movement playing a limited role. Radionuclides injected directly into the rhyolites should migrate laterally very quickly, with travel times as in the downward-transport scenario. Those in the zeolitized tuff-walled portion of the chimney should migrate extremely slowly, as in the upward-transport scenario

Aspects of uranium/thorium series disequilibrium applications to radionuclide migration studies

International Nuclear Information System (INIS)

Ivanovich, M.

1989-11-01

The aim of this paper is to consider the contribution which the uranium/thorium series disequilibrium concept can make to understanding the retardation and transport of radionuclides in the far-field of a radioactive waste repository. In principle, naturally occurring isotopes of uranium, thorium and radium can be regarded as geochemical analogues of the divalent radionuclides and multivalent actinides expected to be present in the radioactive waste inventory. The study of their retardation and/or transport in real rock/water systems which have taken place over geological timescales, can make an important contribution to establishing a rational basis for long-term predictive modelling of radionuclide transport required for safety assessments. (author)

Development of repository-wide radionuclide transport model considering the effects of multiple sources

International Nuclear Information System (INIS)

Hatanaka, Koichiro; Watari, Shingo; Ijiri, Yuji

1999-11-01

Safety assessment of the geological isolation system according to the groundwater scenario has traditionally been conducted based on the signal canister configuration and then the safety of total system has been evaluated based on the dose rates which were obtained by multiplying the migration rates released from the engineered barrier and/or the natural barrier by dose conversion factors and total number of canisters disposed in the repository. The dose conversion factors can be obtained from the biosphere analysis. In this study, we focused on the effect of multiple sources due to the disposal of canisters at different positions in the repository. By taking the effect of multiple sources into consideration, concentration interference in the repository region is possible to take place. Therefore, radionuclide transport model/code considering the effect of concentration interference due to the multiple sources was developed to make assessments of the effect quantitatively. The newly developed model/code was verified through the comparison analysis with the existing radionuclide transport analysis code used in the second progress report. In addition, the effect of the concentration interference was evaluated by setting a simple problem using the newly developed analysis code. This results shows that the maximum park value of the migration rates from the repository was about two orders of magnitude lower than that based on single canister configuration. Since the analysis code was developed by assuming that all canisters disposed of along the one-dimensional groundwater flow contribute to the concentration interference in the repository region, the assumption should be verified by conducting two or three-dimensional analysis considering heterogeneous geological structure as a future work. (author)

Verification and improvement of predictive algorithms for radionuclide migration

International Nuclear Information System (INIS)

Carnahan, C.L.; Miller, C.W.; Remer, J.S.

1984-01-01

This research investigated the adequacy of current numerical codes in simulating geochemical interactions affecting radionuclide migration, the level of complexity required in chemical algorithms of transport models, and the validity of the constant-k/sub D/ concept in chemical transport modeling. An initial survey of the literature led to the conclusion that existing numerical codes did not encompass the full range of chemical and physical phenomena influential in radionuclide migration

Hydrology and Radionuclide Migration Program: 1989 progress report

International Nuclear Information System (INIS)

Marsh, K.V.

1992-08-01

This report presents results from the Lawrence Livermore National Laboratory's participation in the Hydrology and Radionuclide Migration Program (HRMP) at the Nevada Test Site (NTS) during fiscal year 1989. The report compares and summarizes studies of radionuclide and stable element transport atf radionuclide and stable the Cheshire and Cambric sites; progress toward the understanding of colloidal particle transport in porous and fractured media; further calibration of Marinelli beaker containers for gamma-ray spectroscopy; and an appendix listing all announced tests fired near the water table through October 1989. Four such tests were fired in FY89. Laboratory and model investigations of colloid transport in porous and fractured media have supported ongoing field investigations at the NTS. Aqueous chemistry has been shown to control colloid attachment and release from clean mineral surfaces. For colloidal deposits on fracture walls, the current experimental program will determine how this material responds to hydrodynamic forcing and if the porous colloidal deposit causes the more rapid transport of colloids than non-sorbing tracers. Fifteen radionuclides are either frequently found or likely to be found in HRMP and other environmental samples. For 3 of these 15 we have calibrated 4 gamma-ray detectors for use with samples contained in Marinelli beakers. Our calibrations for these three nuclides indicate that the technique is accurate and applicable to the types of environmental samples that we analyze

Mobility of Source Zone Heavy Metals and Radionuclides: The Mixed Roles of Fermentative Activity on Fate and Transport of U and Cr. Final Report

Energy Technology Data Exchange (ETDEWEB)

Gerlach, Robin [Montana State Univ., Bozeman, MT (United States); Peyton, Brent M. [Montana State Univ., Bozeman, MT (United States); Apel, William A. [Idaho National Lab., Idaho Falls, ID (United States)

2014-01-29

Various U. S. Department of Energy (DOE) low and medium-level radioactive waste sites contain mixtures of heavy metals, radionuclides and assorted organic materials. In addition, there are numerous sites around the world that are contaminated with a mixture of organic and inorganic contaminants. In most sites, over time, water infiltrates the wastes, and releases metals, radionuclides and other contaminants causing transport into the surrounding environment. We investigated the role of fermentative microorganisms in such sites that may control metal, radionuclide and organics migration from source zones. The project was initiated based on the following overarching hypothesis: Metals, radionuclides and other contaminants can be mobilized by infiltration of water into waste storage sites. Microbial communities of lignocellulose degrading and fermenting microorganisms present in the subsurface of contaminated DOE sites can significantly impact migration by directly reducing and immobilizing metals and radionuclides while degrading complex organic matter to low molecular weight organic compounds. These low molecular weight organic acids and alcohols can increase metal and radionuclide mobility by chelation (i.e., certain organic acids) or decrease mobility by stimulating respiratory metal reducing microorganisms. We demonstrated that fermentative organisms capable of affecting the fate of Cr6+, U6+ and trinitrotoluene can be isolated from organic-rich low level waste sites as well as from less organic rich subsurface environments. The mechanisms, pathways and extent of contaminant transformation depend on a variety of factors related to the type of organisms present, the aqueous chemistry as well as the geochemistry and mineralogy. This work provides observations and quantitative data across multiple scales that identify and predict the coupled effects of fermentative carbon and electron flow on the transport of radionuclides, heavy metals and organic contaminants in

Mobility of Source Zone Heavy Metals and Radionuclides: The Mixed Roles of Fermentative Activity on Fate and Transport of U and Cr. Final Report

International Nuclear Information System (INIS)

Gerlach, Robin; Peyton, Brent M.; Apel, William A.

2014-01-01

Various U. S. Department of Energy (DOE) low and medium-level radioactive waste sites contain mixtures of heavy metals, radionuclides and assorted organic materials. In addition, there are numerous sites around the world that are contaminated with a mixture of organic and inorganic contaminants. In most sites, over time, water infiltrates the wastes, and releases metals, radionuclides and other contaminants causing transport into the surrounding environment. We investigated the role of fermentative microorganisms in such sites that may control metal, radionuclide and organics migration from source zones. The project was initiated based on the following overarching hypothesis: Metals, radionuclides and other contaminants can be mobilized by infiltration of water into waste storage sites. Microbial communities of lignocellulose degrading and fermenting microorganisms present in the subsurface of contaminated DOE sites can significantly impact migration by directly reducing and immobilizing metals and radionuclides while degrading complex organic matter to low molecular weight organic compounds. These low molecular weight organic acids and alcohols can increase metal and radionuclide mobility by chelation (i.e., certain organic acids) or decrease mobility by stimulating respiratory metal reducing microorganisms. We demonstrated that fermentative organisms capable of affecting the fate of Cr6+, U6+ and trinitrotoluene can be isolated from organic-rich low level waste sites as well as from less organic rich subsurface environments. The mechanisms, pathways and extent of contaminant transformation depend on a variety of factors related to the type of organisms present, the aqueous chemistry as well as the geochemistry and mineralogy. This work provides observations and quantitative data across multiple scales that identify and predict the coupled effects of fermentative carbon and electron flow on the transport of radionuclides, heavy metals and organic contaminants in

Predictive capabilities of a two-dimensional model in the ground water transport of radionuclides

International Nuclear Information System (INIS)

Gureghian, A.B.; Beskid, N.J.; Marmer, G.J.

1978-01-01

The discharge of low-level radioactive waste into tailings ponds is a potential source of ground water contamination. The estimation of the radiological hazards related to the ground water transport of radionuclides from tailings retention systems depends on reasonably accurate estimates of the movement of both water and solute. A two-dimensional mathematical model having predictive capability for ground water flow and solute transport has been developed. The flow equation has been solved under steady-state conditions and the mass transport equation under transient conditions. The simultaneous solution of both equations is achieved through the finite element technique using isoparametric elements, based on the Galerkin formulation. However, in contrast to the flow equation solution, the weighting functions used in the solution of the mass transport equation have a non-symmetric form. The predictive capability of the model is demonstrated using an idealized case based on analyses of field data obtained from the sites of operating uranium mills. The pH of the solution, which regulates the variation of the distribution coefficient (K/sub d/) in a particular site, appears to be the most important factor in the assessment of the rate of migration of the elements considered herein

Structure and function of subsurface microbial communities affecting radionuclide transport and bioimmobilization

Energy Technology Data Exchange (ETDEWEB)

Kostka, Joel E. [Florida State Univ., Tallahassee, FL (United States); Prakash, Om [Florida State Univ., Tallahassee, FL (United States); Green, Stefan J. [Florida State Univ., Tallahassee, FL (United States); Akob, Denise [Florida State Univ., Tallahassee, FL (United States); Jasrotia, Puja [Florida State Univ., Tallahassee, FL (United States); Kerkhof, Lee [Rutgers Univ., New Brunswick, NJ (United States); Chin, Kuk-Jeong [Georgia State Univ., Atlanta, GA (United States); Sheth, Mili [Georgia State Univ., Atlanta, GA (United States); Keller, Martin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Venkateswaran, Amudhan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Elkins, James G. [Univ. of Illinois, Urbana-Champaign, IL (United States); Stucki, Joseph W. [Univ. of Illinois, Urbana-Champaign, IL (United States)

2012-05-01

Our objectives were to: 1) isolate and characterize novel anaerobic prokaryotes from subsurface environments exposed to high levels of mixed contaminants (U(VI), nitrate, sulfate), 2) elucidate the diversity and distribution of metabolically active metal- and nitrate-reducing prokaryotes in subsurface sediments, and 3) determine the biotic and abiotic mechanisms linking electron transport processes (nitrate, Fe(III), and sulfate reduction) to radionuclide reduction and immobilization. Mechanisms of electron transport and U(VI) transformation were examined under near in situ conditions in sediment microcosms and in field investigations. Field sampling was conducted at the Oak Ridge Field Research Center (ORFRC), in Oak Ridge, Tennessee. The ORFRC subsurface is exposed to mixed contamination predominated by uranium and nitrate. In short, we effectively addressed all 3 stated objectives of the project. In particular, we isolated and characterized a large number of novel anaerobes with a high bioremediation potential that can be used as model organisms, and we are now able to quantify the function of subsurface sedimentary microbial communities in situ using state-of-the-art gene expression methods (molecular proxies).

The role of nuclear techniques in the long-term prediction of radionuclide transport

International Nuclear Information System (INIS)

Airey, P.L.; Duerden, P.

1985-01-01

Problems associated with the long-term prediction of the migration of radionuclides, and the role of natural analogues in reducing the inherent uncertainties are discussed. Particular reference is made to the evaluation of uranium ore bodies in the Alligator Rivers region, Northern Territory, as analogues of high-level radioactive waste repositories. A range of nuclear techniques has been used to identify the role of colloids, of alpha recoil and of mineralogy in transport. Specific mention is made of a method being developed which enables models of the migration of solute through fractured rock to be assessed via a combination of alpha track, fission track and PIXE/PIGME techniques

Radionuclide transfer in terrestrial animals

International Nuclear Information System (INIS)

DiGregorio, D.; Kitchings, T.; Van Voris, P.

1978-01-01

The analysis of dispersion of radionuclides in terrestrial food chains, generally, is a series of equations identifying the fractional input and outflow rates from trophic level to trophic level. Data that are prerequisite inputs for these food chain transport models include: (1) identification of specific transport pathway, (2) assimilation at each pathway link, and (3) the turnover rate or retention function by successive receptor species in the appropriate food chain. In this report, assimilation coefficients, biological half-lives, and excretion rates for a wide variety of vertebrate and invertebrate species and radionuclides have been compiled from an extensive search of the available literature. Using the information accumulated from the literature, correlations of nuclide metabolism and body weight are also discussed. (author)

Nominal Range Sensitivity Analysis of peak radionuclide concentrations in randomly heterogeneous aquifers

International Nuclear Information System (INIS)

Cadini, F.; De Sanctis, J.; Cherubini, A.; Zio, E.; Riva, M.; Guadagnini, A.

2012-01-01

Highlights: ► Uncertainty quantification problem associated with the radionuclide migration. ► Groundwater transport processes simulated within a randomly heterogeneous aquifer. ► Development of an automatic sensitivity analysis for flow and transport parameters. ► Proposal of a Nominal Range Sensitivity Analysis approach. ► Analysis applied to the performance assessment of a nuclear waste repository. - Abstract: We consider the problem of quantification of uncertainty associated with radionuclide transport processes within a randomly heterogeneous aquifer system in the context of performance assessment of a near-surface radioactive waste repository. Radionuclide migration is simulated at the repository scale through a Monte Carlo scheme. The saturated groundwater flow and transport equations are then solved at the aquifer scale for the assessment of the expected radionuclide peak concentration at a location of interest. A procedure is presented to perform the sensitivity analysis of this target environmental variable to key parameters that characterize flow and transport processes in the subsurface. The proposed procedure is exemplified through an application to a realistic case study.

Particle and solute migration in porous media. Modeling of simultaneous transport of clay particles and radionuclides in a salinity gradient

International Nuclear Information System (INIS)

Faure, M.H.

1994-03-01

Understanding the mechanisms which control the transient transport of particles and radionuclides in natural and artificial porous media is a key problem for the assessment of safety of radioactive waste disposals. An experimental study has been performed to characterize the clayey particle mobility in porous media: a laboratory- made column, packed with an unconsolidated sand bentonite (5% weight) sample, is flushed with a salt solution. An original method of salinity gradient allowed us to show and to quantify some typical behaviours of this system: threshold effects in the peptization of particles, creation of preferential pathways, formation of immobile water zones induce solute-transfer limitation. The mathematical modelling accounts for a phenomenological law, where the distribution of particles between the stagnant water zone and the porous medium is a function of sodium chloride concentration. This distribution function is associated with a radionuclide adsorption model, and is included in a convective dispersive transport model with stagnant water zones. It allowed us to simulate the particle and solute transport when the salt environment is modified. The complete model has been validated with experiments involving cesium, calcium and neptunium in a sodium chloride gradient. (author). refs., figs., tabs

Kinetic modeling of microbially-driven redox chemistry of radionuclides in subsurface environments: Coupling transport, microbial metabolism and geochemistry

International Nuclear Information System (INIS)

Wang, Yifeng; Papenguth, Hans W.

2000-01-01

Microbial degradation of organic matter is a driving force in many subsurface geochemical systems, and therefore may have significant impacts on the fate of radionuclides released into subsurface environments. In this paper, the authors present a general reaction-transport model for microbial metabolism, redox chemistry, and radionuclide migration in subsurface systems. The model explicitly accounts for biomass accumulation and the coupling of radionuclide redox reactions with major biogeochemical processes. Based on the consideration that the biomass accumulation in subsurface environments is likely to achieve a quasi-steady state, they have accordingly modified the traditional microbial growth kinetic equation. They justified the use of the biogeochemical models without the explicit representation of biomass accumulation, if the interest of modeling is in the net impact of microbial reactions on geochemical processes. They then applied their model to a scenario in which an oxic water flow containing both uranium and completing organic ligands is recharged into an oxic aquifer in a carbonate formation. The model simulation shows that uranium can be reduced and therefore immobilized in the anoxic zone created by microbial degradation

Kinetic modeling of microbially-driven redox chemistry of radionuclides in subsurface environments: Coupling transport, microbial metabolism and geochemistry

Energy Technology Data Exchange (ETDEWEB)

WANG,YIFENG; PAPENGUTH,HANS W.

2000-05-04

Microbial degradation of organic matter is a driving force in many subsurface geochemical systems, and therefore may have significant impacts on the fate of radionuclides released into subsurface environments. In this paper, the authors present a general reaction-transport model for microbial metabolism, redox chemistry, and radionuclide migration in subsurface systems. The model explicitly accounts for biomass accumulation and the coupling of radionuclide redox reactions with major biogeochemical processes. Based on the consideration that the biomass accumulation in subsurface environments is likely to achieve a quasi-steady state, they have accordingly modified the traditional microbial growth kinetic equation. They justified the use of the biogeochemical models without the explicit representation of biomass accumulation, if the interest of modeling is in the net impact of microbial reactions on geochemical processes. They then applied their model to a scenario in which an oxic water flow containing both uranium and completing organic ligands is recharged into an oxic aquifer in a carbonate formation. The model simulation shows that uranium can be reduced and therefore immobilized in the anoxic zone created by microbial degradation.

Fate and transport of radionuclides in soil-water environment. Review.

Science.gov (United States)

Konoplev, Aleksei

2017-04-01

is up to one order of magnitude higher than in Chernobyl. Long-term dynamics of radionuclide concentrations in rivers is approached from the standpoint of basic mechanisms of radionuclide sorption-desorption, fixation, vertical migration in catchment soils. Corresponding semi-empirical models are presented and discussed. For the Chernobyl case, radiostrontium (r-Sr) was shown to be more mobile and moving faster in dissolved state with surface runoff and river water in comparison with r-Cs. Similar pattern was observed for Mayak area in South Ural (Russia), where r-Sr was traced up to 1500 km away from the release point migrating through Techa-Iset'-Tobol-Irtysh-Ob' river system. On the other hand, r-Cs bound to clay particles settles down in Techa river reservoirs and is transported with river water only insignificantly. For the first 3 years after the accident vertical migration of r-Cs in soils of Fukushima catchments was found to be faster than in Chernobyl due to higher air temperature, higher precipitation and higher biological activity in top soil. However, with time this process slows down because of higher r-Cs retardation in Fukushima soils. In Fukushima case, extreme floods during typhoons lead to substantial reduction in dose rate on floodplain areas due to sedimentation of relatively clean material and burial of contaminated top soil layer. In general, due to higher precipitation, higher temperatures and higher biological activities in soils, self-purification of the environment and natural attenuation in Fukushima is essentially faster than in Chernobyl area.

Toward a Mechanistic Source Term in Advanced Reactors: Characterization of Radionuclide Transport and Retention in a Sodium Cooled Fast Reactor

Energy Technology Data Exchange (ETDEWEB)

Brunett, Acacia J.; Bucknor, Matthew; Grabaskas, David

2016-04-17

A vital component of the U.S. reactor licensing process is an integrated safety analysis in which a source term representing the release of radionuclides during normal operation and accident sequences is analyzed. Historically, source term analyses have utilized bounding, deterministic assumptions regarding radionuclide release. However, advancements in technical capabilities and the knowledge state have enabled the development of more realistic and best-estimate retention and release models such that a mechanistic source term assessment can be expected to be a required component of future licensing of advanced reactors. Recently, as part of a Regulatory Technology Development Plan effort for sodium cooled fast reactors (SFRs), Argonne National Laboratory has investigated the current state of knowledge of potential source terms in an SFR via an extensive review of previous domestic experiments, accidents, and operation. As part of this work, the significant sources and transport processes of radionuclides in an SFR have been identified and characterized. This effort examines all stages of release and source term evolution, beginning with release from the fuel pin and ending with retention in containment. Radionuclide sources considered in this effort include releases originating both in-vessel (e.g. in-core fuel, primary sodium, cover gas cleanup system, etc.) and ex-vessel (e.g. spent fuel storage, handling, and movement). Releases resulting from a primary sodium fire are also considered as a potential source. For each release group, dominant transport phenomena are identified and qualitatively discussed. The key product of this effort was the development of concise, inclusive diagrams that illustrate the release and retention mechanisms at a high level, where unique schematics have been developed for in-vessel, ex-vessel and sodium fire releases. This review effort has also found that despite the substantial range of phenomena affecting radionuclide release, the

Behavioural feedback to risk variation ensues from unsatisfied appetency.

Science.gov (United States)

Dussault, C

1996-07-01

For a long time, but particularly since the last two decades, the phenomenon of behavioural feedback to risk variation, especially to highway safety measures, has been the subject of numerous papers and debates. It has been advanced that human behaviour ensues from the interaction between two motivational systems: (1) appetency, governed by a homeostasic mechanism, wherein the individual seeks to satisfy needs, and (2) aversion, guided by the principle of zero aversion, whereby the individual seeks to avoid aversive stimuli. When an individual considers the possibility of undertaking an action, he weighs the advantages (appetency) and the disavantages (aversion). If the appetency proves to be stronger than the aversion, the action is completed and ipso facto, the individual accepts the risk associated with it. In this article, it is suggested that the behavioural feedback following a variation in the risk (aversion) ensues from unsatisfied appetency. If the unsatisfied appetency is nil (the individual is already satisfied), a drop in the aversive constraint (e.g. lowered risk of an accident) will not cause any behavioural feedback. On the other hand, if there is an unsatisfied appetency (the individual is not fully satisfied), a drop in the aversive constraint will bring about behavioural feedback in proportion to the level of unsatisfied appetency. Cases in which behavioural feedback is likely to arise and the implications for public policy-making are briefly discussed.

Model validation studies of water flow and radionuclide transport in vegetated soils using lysimeter data

Energy Technology Data Exchange (ETDEWEB)

Butler, A.; Jining Chen [Imperial College of Science, Technology and Medicine, London (United Kingdom)] [and others

1996-09-01

Model Uncertainty and Validation was one of the four themes of BIOMOVS II which had been identified by the programme's steering committee. It arose out of a concern that biosphere assessment models are generally simplified representations of highly complex environmental systems which, therefore, include a degree of uncertainty in their outputs. This uncertainty may be due to inadequate representations of the physical, chemical and biological processes; issues associated with scaling up highly non-linear systems; problems of model identification, in particular user interpretation. Therefore, during the course of the 5 year (1991-1996) BIOMOVS II programme a number of working sub-groups reestablished to address these issues. This document is the final report of the Prediction of Upward Migration of Radionuclides in Lysimeters sub-group which was established towards the end of the programme, late in 1994. It describes the 'blind' application of various hydrological and radiochemical transport models to experiment data derived from vegetated lysimeters. In order to investigate soil-to-plant transfer processes affecting the radionuclide migration from contaminated near surface water tables into arable crops, a lysimeter experiment has been undertaken at Imperial College, funded by UK Nirex Ltd. Detailed observations of climate, soil hydrology, plant growth and radiochemical migration were collected on the uptake of various radionuclides by a winter wheat crop. A selected set of data was made available to members of BIOMOVS II in order to allow them to test relevant components of current versions of assessment code. This was a challenging task owing to the rather unusual experimental design, in particular, the introduction of radionuclides at the base of the lysimeter, 5 cm below a fixed water table, and their subsequent upward migration through the soil. The comprehensive hydrological data set available provided various modelers, particularly those

Model validation studies of water flow and radionuclide transport in vegetated soils using lysimeter data

International Nuclear Information System (INIS)

Butler, A.; Jining Chen

1996-09-01

Model Uncertainty and Validation was one of the four themes of BIOMOVS II which had been identified by the programme's steering committee. It arose out of a concern that biosphere assessment models are generally simplified representations of highly complex environmental systems which, therefore, include a degree of uncertainty in their outputs. This uncertainty may be due to inadequate representations of the physical, chemical and biological processes; issues associated with scaling up highly non-linear systems; problems of model identification, in particular user interpretation. Therefore, during the course of the 5 year (1991-1996) BIOMOVS II programme a number of working sub-groups reestablished to address these issues. This document is the final report of the Prediction of Upward Migration of Radionuclides in Lysimeters sub-group which was established towards the end of the programme, late in 1994. It describes the 'blind' application of various hydrological and radiochemical transport models to experiment data derived from vegetated lysimeters. In order to investigate soil-to-plant transfer processes affecting the radionuclide migration from contaminated near surface water tables into arable crops, a lysimeter experiment has been undertaken at Imperial College, funded by UK Nirex Ltd. Detailed observations of climate, soil hydrology, plant growth and radiochemical migration were collected on the uptake of various radionuclides by a winter wheat crop. A selected set of data was made available to members of BIOMOVS II in order to allow them to test relevant components of current versions of assessment code. This was a challenging task owing to the rather unusual experimental design, in particular, the introduction of radionuclides at the base of the lysimeter, 5 cm below a fixed water table, and their subsequent upward migration through the soil. The comprehensive hydrological data set available provided various modelers, particularly those involved in tritium

Three-dimensional simulation of radionuclides dispersion in the stratified estuaries

International Nuclear Information System (INIS)

Koziy, L.; Margvelashvili, N.; Maderich, V.; Zheleznyak, M.

1999-01-01

THREE-dimensional model of TOXicants transport (THREETOX) was developed for assessment of potential and real emergency situations in the coastal area of seas and the inland water bodies. It includes the high resolution numerical hydrodynamic submodel, dynamic-thermodynamic ice submodel, submodels of suspended sediment and radionuclide transport. The results of two case studies are described. The first one concerns to two-year simulation of the Chernobyl origin radionuclide transport through Dnieper-Bug estuary into the Black sea. In the second case study the simulations were performed for the assessment of potential emergency situation caused by the radionuclide release from reactors and containers with the liquid radioactive wastes scuttled in the Novaya Zemlya fjords (Tsivolki, Stepovogo and Abrosimov). The presented results demonstrate the capability of THREETOX model to describe the wide spatial and temporal range of transport processes in the coastal area of seas. (author)

Bentonite erosion: effects on the long term performance of the engineered barrier and radionuclide transport - The BELBAR project

International Nuclear Information System (INIS)

Sellin, P.; Sundman, D.; Bailey, L.; Missana, T.; Schaefer, T.; Cervinka, R.; Koskinen, K.

2012-01-01

Document available in extended abstract form only. BELBaR is a Collaborative Project within the Seventh Framework Programme of the European Atomic Energy Community (Euratom) for nuclear research and training activities. The main aim of BELBaR is to increase knowledge of the processes that control clay colloid stability, generation and its ability to transport radionuclides. The overall purpose of the project is to come up with a new way of treating issues in long-term safety/performance assessment. The project started March 1, 2012 and has a duration of 48 months. The project has 14 partners from seven European countries. The main aim of BELBaR is to reduce the uncertainties in the description of the effect of clay colloids on the long term performance of the engineered barrier and on radionuclide transport as illustrated in Figure 1. This is done by: - Improving the understanding on when bentonite colloids are unstable. For a given site/site evolution, this is critical information, since it determines whether or not clay colloids need to be included in the long-term assessment. - Improving the quantitative models for erosion on the bentonite barrier for the cases when the colloids are stable - Improving the understanding of how radionuclides attach to clay colloids. This information will be used to formulate improved transport models for the assessment of radionuclide transport in the geosphere. To meet the main aim a number of experimental and modelling activities will be undertaken within the project. BELBaR consists of six RTD (research and technical development) work packages and one project management work package. WP1 will have the responsibility to ensure that that the type and values of the parameters selected for experimental and modelling work are those that represent as much as possible the full range of conditions and situations that can be expected in a repository. Drawing on the work undertaken in WP 2 to 5, the general objective of this work package

Stochastic analysis of contaminant transport in porous media: analysis of a two-member radionuclide chain

International Nuclear Information System (INIS)

Bonano, E.J.; Shipers, L.R.

1987-01-01

In this study the authors extend previous stochastic analyses of contaminant transport in geologic media for a single species to a chain of two species. The authors particular application is the quantification of uncertainties due to lack of characterization of the spatial variability of hydrologic parameters on transport of radionuclides from a high-level waste repository to the biosphere. Radionuclide chains can have a significant impact on demonstrating compliance (or violation) of standards regulating the release to the environment accessible to humans. Two approaches for determining the cross-covariance terms in the mean concentration equations are presented. One uses a Taylor expansion to obtain the cross-covariance between the velocity and concentration fluctuations, while the other is based on a Fourier-Laplace double transform method. For the conditions of interest here, the difference between these two approaches are expected to be small. In addition, the variances are calculated in a unique way by solving another associated partial differential equation. A parametric study is carried out to examine the sensitivity of the mean concentration of the two species and their corresponding variances and cross-covariance on the parameters associated with the structure of the stochastic velocity field. It is found that the dependent variables are most sensitive to the intensity and correlation length of the velocity fluctuations. The magnitude of the variances and cross-covariance of the concentrations are proportional to the magnitude of the mean concentrations which depend on inlet concentration boundary conditions

In-situ radionuclide transport and preferential groundwater flows at INEEL (Idaho): Decay-series disequilibrium studies

International Nuclear Information System (INIS)

Luo, S.; Ku, T.L.; Roback, R.; Murrell, M.; McLing, T.L.

2000-01-01

Uranium and thorium-decay series disequilibria in groundwater occur as a result of water-rock interactions, and they provide site-specific, natural analog information for assessment of in-situ, long-term migration of radionuclides in the far field of a nuclear waste disposal site. In this study, a mass balance model was used to relate the decay-series radionuclide distributions among solution, sorbed and solid phases in an aquifer system to processes of water transport, sorption-desorption, dissolution-precipitation, radioactive ingrowth-decay, and α recoil. Isotopes of U and Rn were measured in 23 groundwater samples collected from a basaltic aquifer at the Idaho National Engineering and Environmental Laboratory (INEEL), Idaho. The results show that groundwater activities of Th and Ra isotopes are 2--4 orders lower than those of their U progenitors. Modeling of the observed disequilibria places the following constraints on the time scale of radionuclide migration and water-rock interaction at INEEL: (1) Time for sorption is minutes for Ra and Th; time for desorption is days for Ra and years for Th; and time for precipitation is days for Th, years for Ra, and centuries for U. (2) Retardation factors due to sorption average > 10 6 for 232 Th, approximately10 4 for 226 Ra, and approximately10 3 for 238 U. (3) Dissolution rates of rocks are approximately70 to 800 mg/L/y. (4) Ages of groundwater range from 222 Rn occur near the groundwater recharging sites as well as in the major flow pathways. Decay of the sorbed parent radionuclides (e.g., 226 Ra and 228 Ra) on micro-fracture surfaces constitutes an important source of their daughter ( 222 Rn and 228 Th) activities in groundwater

Transuranic radionuclides dispersed into the environment at accident sites, a bibliography

International Nuclear Information System (INIS)

Stoker, A.C.; Noshkin, V.E.; Wong, K.M.

1994-07-01

The purpose of this project was to compile a bibliography of references containing environmental transuranic radionuclide data. The authors intent was to identify those parameters affecting transuranic radionuclide transport that may be generic and those that may be dependent on chemical form and/or environmental conditions. An understanding of the unique characteristics and similarities between source terms and environmental conditions relative to transuranic radionuclide transport and cycling will provide the ability to assess and predict the long term impact on man and the environment. An additional goal of the literature review, was to extract the ranges of environmental transuranic radionuclide data from the identified references for inclusion in a data base. Related to source term, these ranges of data can be used to calculate the dose to man from the radionuclides, and to perform uncertainty analyses on these dose assessments

Three-Dimensional Radionuclide Transport Through the Unsaturated Zone of the Yucca Mountain Site 3 Colloids

International Nuclear Information System (INIS)

G. J. Moridis; Y. Seol

2007-01-01

The authors investigated colloid transport in the unsaturated fractured zone by means of three-dimensional site-scale numerical model under present-day climate infiltration, considering varying colloid diameters, kinetic declogging, and filtration. The radionuclide transport model was used to simulate continuous release of colloids into fractures throughout the proposed repository, in which any components of engineered barrier system such as waste package or drip shield were not considered. the results of the study indicate the importance of subsurface geology and site hydrology, i.e., the presence of faults (they dominate and control transport), fractures (the main migration pathways), and the relative distribution of zeolitic and vitric tuffs. The simulations indicate that (1) colloid transport is not significantly affected by varying the filtration parameters, (2) travel time to the water table decreases with the colloid size, (3) larger colloids show little retardation whereas very small ones are retarded significantly, and (4) fracture filtration can have an impact on transport. Because of uncertainties in the fundamentals of colloid transport and an extremely conservative approach (based on an improbably adverse worst-case scenario), caution should be exercised in the analysis and interpretation of the 3-D simulation results. The results discussed here should be viewed as an attempt to identify and evaluate the mechanisms, processes, and geological features that control colloidal transport

Modeling the Long-term Transport and Accumulation of Radionuclides in the Landscape for Derivation of Dose Conversion Factors

International Nuclear Information System (INIS)

Avila, Rodolfo Moreno; Ekstroem, Per-Anders; Kautsky, Ulrik

2006-01-01

To evaluate the radiological impact of potential releases to the biosphere from a geological repository for spent nuclear fuel, it is necessary to assess the long-term dynamics of the distribution of radionuclides in the environment. In this paper, we propose an approach for making prognoses of the distribution and fluxes of radionuclides released from the geosphere, in discharges of contaminated groundwater, to an evolving landscape. The biosphere changes during the temperate part (spanning approximately 20,000 years) of an interglacial period are handled by building biosphere models for the projected succession of situations. Radionuclide transport in the landscape is modeled dynamically with a series of interconnected radioecological models of those ecosystem types (sea, lake, running water, mire, agricultural land and forest) that occur at present, and are projected to occur in the future, in a candidate area for a geological repository in Sweden. The transformation between ecosystems is modeled as discrete events occurring every thousand years by substituting one model by another. Examples of predictions of the radionuclide distribution in the landscape are presented for several scenarios with discharge locations varying in time and space. The article also outlines an approach for estimating the exposure of man resulting from all possible reasonable uses of a potentially contaminated landscape, which was used for derivation of Landscape Dose Factors

MASCOT user's guide--Version 2.0: Analytical solutions for multidimensional transport of a four-member radionuclide decay chain in ground water

International Nuclear Information System (INIS)

Gureghian, A.B.

1988-07-01

The MASCOT code computes the two- and three-dimensional space-time dependent convective-dispersive transport of a four-member radionuclide decay chain in unbounded homogeneous porous media, for constant and radionuclide-dependent release, and assuming steady- state isothermal ground-water flow and parallel streamlines. The model can handle a single or multiple finite line source or a Gaussian distributed source in the two-dimensional case, and a single or multiple patch source or bivariate-normal distributed source in the three-dimensional case. The differential equations are solved by Laplace and Fourier transforms and a Gauss-Legendre integration scheme. 33 figs., 3 tabs

Soil Fauna Transport Versus Radionuclide Migration (invited paper)

International Nuclear Information System (INIS)

Bunnenberg, C.; Taeschner, M.

2000-01-01

From a questionnaire on radioecological topics circulated in the framework of the IUR/EURADOS/EULEP Concerted Action supported by the EC it was concluded that the effect of soil fauna on the redistribution of radionuclides in soils has never been given sufficient attention. The limited data in existence suggest than faunal effects on displacement of radionuclides may be dominant over physicochemical migration. On the basis of a given dataset, an earthworm model is presented which shows that the activity decrease in the top soil layer due to bioturbation may compete with fast physicochemical migration at rates of 1 to 10 cm.y -1 . The model represents a suggestion of how to treat faunal actions and what kind of data are necessary to operate such models. (author)

Performance assessment model development and parameter acquisition for analysis of the transport of natural radionuclides in a Mediterranean watershed

International Nuclear Information System (INIS)

Agueero, Almudena

2005-01-01

This paper describes the methodology developed to construct a model for predicting the behaviour of the natural radioisotopes of U, Th and Ra in a Mediterranean watershed. The methodology includes the development of the performance assessment model, obtaining water flow and radiological parameters based on experimental data and analysis of results. The model, which accounts for both water flows and mass balances of the radionuclides in a semi-natural environment, provides assessments of radionuclide behaviour in grassland and agricultural soils, rivers and reservoirs, including the processes of radionuclide migration through land and water and interactions between both. From field and laboratory data, it has been possible to obtain parameters for the driving processes considered in the model, water fluxes, source term definition, soil to plant transfer factors and distribution coefficient values. Ranges of parameter values obtained have shown good agreement with published literature data. This general methodological approach was developed to be extended to other radionuclides for the modelling of a biosphere watershed in the context of performance assessment of a High Level Waste (HLW) repository under Mediterranean climate conditions, as well as for forecasting radionuclide transport under similar Mediterranean conditions that will occur in the future in other areas. The application of sensitivity and uncertainty analysis was intended to identify key uncertainties with the aim of setting priorities for future research. The model results for the activity concentration in the reservoir indicate that for 238 U and 230 Th the most relevant parameter is the initial concentrations of the radionuclides in the reservoir sediments. However, for 226 Ra the most important parameter is the precipitation rate over the whole watershed

Radionuclide retardation project at GTS - An overview of lessons learned and ongoing experiments

International Nuclear Information System (INIS)

Moeri, A.

2001-01-01

The joint Nagra/JNC Radionuclide Migration Programme has now been ongoing for more than 15 years in Nagra's Grimsel Test Site (GTS). The main aim of the programme has been the direct testing of radionuclide transport models in as realistic a manner as possible. The understanding and modelling of both the processes and the structures influencing radionuclide transport/retardation in fractured granitic host rocks have matured as has the experimental technology, which has contributed to develop confidence in the applicability of the underlying research models in a repository performance assessment. In this paper, three in situ experiments which were carried out in a discrete granitic shear zone are briefly presented: The Migration Experiment (MI), the Excavation Experiment (EP) and the ongoing Colloid and Radionuclide Retardation Experiment (CRR). Each project expanded on the experimental experience and research results from the preceding experiment. MI provided a sound data base of in situ tracer breakthrough curves which was used to derive relevant transport parameters by inverse modelling in order to enhance the capability for predictive modelling of tracer transport in a granitic shear zone. The Excavation Project (EP) then focussed on the excavation of the dipole flow field in order to describe the flow paths within the shear zone dipole and the retardation behaviour of sorbing radionuclides that are relevant to post-closure safety. The ongoing CRR experiment actually investigates the influence of bentonite colloids on the radionuclide transport behaviour through a fractured granitic host rock. Again, the experience in planning and handling of complex tracer field experiments gained in the proceeding experiments will be availed. The methodology adopted for the geological and hydrological characterisation of water-conducting features and the simplification of this characterisation for modelling purposes proved to be indeed effective on the modelling of

Surface charge accumulation of particles containing radionuclides in open air.

Science.gov (United States)

Kim, Yong-Ha; Yiacoumi, Sotira; Tsouris, Costas

2015-05-01

Radioactivity can induce charge accumulation on radioactive particles. However, electrostatic interactions caused by radioactivity are typically neglected in transport modeling of radioactive plumes because it is assumed that ionizing radiation leads to charge neutralization. The assumption that electrostatic interactions caused by radioactivity are negligible is evaluated here by examining charge accumulation and neutralization on particles containing radionuclides in open air. A charge-balance model is employed to predict charge accumulation on radioactive particles. It is shown that particles containing short-lived radionuclides can be charged with multiple elementary charges through radioactive decay. The presence of radioactive particles can significantly modify the particle charge distribution in open air and yield an asymmetric bimodal charge distribution, suggesting that strong electrostatic particle interactions may occur during short- and long-range transport of radioactive particles. Possible effects of transported radioactive particles on electrical properties of the local atmosphere are reported. The study offers insight into transport characteristics of airborne radionuclides. Results are useful in atmospheric transport modeling of radioactive plumes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Natural and Synthetic Barriers to Immobilize Radionuclides

International Nuclear Information System (INIS)

Um, W.

2011-01-01

The experiments of weathering of glass waste form and the reacted sediments with simulated glass leachates show that radionuclide sequestration can be significantly enhanced by promoting the formation of secondary precipitates. In addition, synthetic phosphate-bearing nanoporous material exhibits high stability at temperature and has a very high K d value for U(VI) removal. Both natural and synthetic barrier materials can be used as additional efficient adsorbents for retarding transport of radionuclides for various contaminated waste streams and waste forms present at U. S. Department of Energy clean-up sites and the proposed geologic radioactive waste disposal facility. In the radioactive waste repository facility, natural or synthetic materials are planned to be used as a barrier material to immobilize and retard radionuclide release. The getter material can be used to selectively scavenge the radionuclide of interest from a liquid waste stream and subsequently incorporate the loaded getters in a cementitious or various monolithic waste forms. Also, the getter material is to reduce the release of radionuclides from monolithic waste forms. Also, the getter material is to reduce the release of radionuclides from monolithic waste forms. Also, the getter material is to reduce the release of radionuclides form monolithic waste forms by being emplaced as a backfill barrier material around the wastes or waste form to minimize the potential around the wastes or waste form to minimize the potential hazard of leached radioactive wastes. The barrier material should be highly efficient to sequester radionuclides and possess physical and chemical stability for long-term exposure to severe weathering conditions. Because potential leaching of radionuclides depends on various environmental and weathering conditions of the near-field repository, the barrier materials must be durable and not disintegrate under a range of moisture, temperature, pressure, radiation, Eh, ph. and

Field test facility for monitoring water/radionuclide transport through partially saturated geologic media: design, construction, and preliminary description. Appendix I. Engineering drawings

International Nuclear Information System (INIS)

Phillips, S.J.; Campbell, A.C.; Campbell, M.D.; Gee, G.W.; Hoober, H.H.; Schwarzmiller, K.O.

1979-11-01

The engineering plans for a test facility to monitor radionuclide transport in water through partially saturated geological media are included. Drawings for the experimental set-up excavation plan and details, lysimeter, pad, access caisson, and caisson details are presented

Modeling of Groundwater Flow and Radionuclide Transport at the Climax Mine sub-CAU, Nevada Test Site

International Nuclear Information System (INIS)

K. Pohlmann; M. Ye; D. Reeves; M. Zavarin; D. Decker; J. Chapman

2007-01-01

The Yucca Flat-Climax Mine Corrective Action Unit (CAU) on the Nevada Test Site comprises 747 underground nuclear detonations, all but three of which were conducted in alluvial, volcanic, and carbonate rocks in Yucca Flat. The remaining three tests were conducted in the very different hydrogeologic setting of the Climax Mine granite stock located in Area 15 at the northern end of Yucca Flat. As part of the Corrective Action Investigation (CAI) for the Yucca Flat-Climax Mine CAU, models of groundwater flow and radionuclide transport will be developed for Yucca Flat. However, two aspects of these CAU-scale models require focused modeling at the northern end of Yucca Flat beyond the capability of these large models. First, boundary conditions and boundary flows along the northern reaches of the Yucca Flat-Climax Mine CAU require evaluation to a higher level of detail than the CAU-scale Yucca Flat model can efficiently provide. Second, radionuclide fluxes from the Climax tests require analysis of flow and transport in fractured granite, a unique hydrologic environment as compared to Yucca Flat proper. This report describes the Climax Mine sub-CAU modeling studies conducted to address these issues, with the results providing a direct feed into the CAI for the Yucca Flat-Climax Mine CAU. Three underground nuclear detonations were conducted for weapons effects testing in the Climax stock between 1962 and 1966: Hard Hat, Pile Driver, and Tiny Tot. Though there is uncertainty regarding the position of the water table in the stock, it is likely that all three tests were conducted in the unsaturated zone. In the early 1980s, the Spent Fuel Test-Climax (SFT-C) was constructed to evaluate the feasibility of retrievable, deep geologic storage of commercial nuclear reactor wastes. Detailed mapping of fractures and faults carried out for the SFT-C studies greatly expanded earlier data sets collected in association with the nuclear tests and provided invaluable information for

Modeling of Groundwater Flow and Radionuclide Transport at the Climax Mine sub-CAU, Nevada Test Site

Energy Technology Data Exchange (ETDEWEB)

K. Pohlmann; M. Ye; D. Reeves; M. Zavarin; D. Decker; J. Chapman

2007-09-28

The Yucca Flat-Climax Mine Corrective Action Unit (CAU) on the Nevada Test Site comprises 747 underground nuclear detonations, all but three of which were conducted in alluvial, volcanic, and carbonate rocks in Yucca Flat. The remaining three tests were conducted in the very different hydrogeologic setting of the Climax Mine granite stock located in Area 15 at the northern end of Yucca Flat. As part of the Corrective Action Investigation (CAI) for the Yucca Flat-Climax Mine CAU, models of groundwater flow and radionuclide transport will be developed for Yucca Flat. However, two aspects of these CAU-scale models require focused modeling at the northern end of Yucca Flat beyond the capability of these large models. First, boundary conditions and boundary flows along the northern reaches of the Yucca Flat-Climax Mine CAU require evaluation to a higher level of detail than the CAU-scale Yucca Flat model can efficiently provide. Second, radionuclide fluxes from the Climax tests require analysis of flow and transport in fractured granite, a unique hydrologic environment as compared to Yucca Flat proper. This report describes the Climax Mine sub-CAU modeling studies conducted to address these issues, with the results providing a direct feed into the CAI for the Yucca Flat-Climax Mine CAU. Three underground nuclear detonations were conducted for weapons effects testing in the Climax stock between 1962 and 1966: Hard Hat, Pile Driver, and Tiny Tot. Though there is uncertainty regarding the position of the water table in the stock, it is likely that all three tests were conducted in the unsaturated zone. In the early 1980s, the Spent Fuel Test-Climax (SFT-C) was constructed to evaluate the feasibility of retrievable, deep geologic storage of commercial nuclear reactor wastes. Detailed mapping of fractures and faults carried out for the SFT-C studies greatly expanded earlier data sets collected in association with the nuclear tests and provided invaluable information for

Radionuclide distributions and sorption behavior in the Susquehanna--Chesapeake Bay System

International Nuclear Information System (INIS)

Olsen, C.R.; Larsen, I.L.; Lowry, P.D.; McLean, R.I.; Domotor, S.L.

1989-01-01

Radionuclides released into the Susquehanna--Chesapeake System from the Three Mile Island, Peach Bottom, and Calvert Cliffs nuclear power plants are partitioned among dissolved, particulate, and biological phases and may thus exist in a number of physical and chemical forms. In this project, we have measured the dissolved and particulate distributions of fallout 137 Cs; reactor-released 137 Cs, 134 Cs, 65 Zn, 60 Co, and 58 Co; and naturally occurring 7 Be and 210 Pb in the lower Susquehanna River and Upper Chesapeake Bay. In addition, we chemically leached suspended particles and bottom sediments in the laboratory to determine radionuclide partitioning among different particulate-sorbing phases to complement the site-specific field data. This information has been used to document the important geochemical processes that affect the transport, sorption, distribution, and fate of reactor-released radionuclides (and by analogy, other trace contaminants) in this river-estuarine system. Knowledge of the mechanisms, kinetic factors, and processes that affect radionuclide distributions is crucial for predicting their biological availability, toxicity, chemical behavior, physical transport, and accumulation in aquatic systems. The results from this project provide the information necessary for developing accurate radionuclide-transport and biological-uptake models. 76 refs., 12 figs

Evaluation of radionuclide migration in the homogeneous system of a geological repository

International Nuclear Information System (INIS)

Prvakova, S.; Duran, J.; Necas, V.

2005-01-01

The aim of this paper is to study radionuclide migration and release from a deep underground repository situated in a clay formation. An insight into the processes influencing the radionuclide transport in the near field and far field will be presented. For the calculation, a set of radionuclides has been chosen, considering the half-life, decay chains, capacity of the sorption, solubility limits and diffusion coefficients. The migration of radionuclides is dependent on transport properties of the particular nuclide. Due to the low hydraulic conductivity of the backfill material and clay geological formation, the transport in the repository occurs mainly by diffusion. The migration rate will be influenced by the water chemistry, solubility, retardation and diffusive properties of the nuclides, and the water flow rate in the clay. The release rates of radionuclides from the geosphere to the biosphere will be converted into the indicative dose rates using dose conversion factors for ingestion. The impact of the critical group is considered via consumption of meat, root vegetables and drinking water from wells. (author)

Movement of radionuclides through unsaturated soils

International Nuclear Information System (INIS)

de Sousa, F.N.C.

1985-01-01

The advantages of the disposal of low-level radioactive wastes in the unsaturated zone above the fluctuations of the water table have been recognized for some time. However, most the numerical models used to simulate the environmental impact of a shallow land burial site assume that the soils surrounding the waste forms are saturated; this assumption may lead, in many cases, to unrealistic large leach and water flow rates. The main purpose of this study was the development of a procedure which could give a reliable prediction on the movement of radionuclides from shallow land burial sites located in the unsaturated zone. In order to accomplish this objective three different soils having different sand, silt, and clay fractions were selected and characterized. These soils were then used to fill a number of flow columns that were used in tests designed to provide input data for the flow and transport models. A one-dimensional finite element model was developed in order to simulate the water flow and radionuclide transport through unsaturated soils. The results obtained showed that the model accurately described the transport of radionuclides through saturated-unsaturated soils. Simulations were done, for all three soils, involving different degrees of soil saturation, and the results showed that assuming the soils are always saturated may lead to nuclide transport times which are orders of magnitude larger than the real ones, depending on the clay percentage present in the soil

Studies on distribution coefficient (Kd) of naturally occurring radionuclides in geological matrices

International Nuclear Information System (INIS)

Pandit, G.G.

2014-01-01

Accurate prediction of fate and transport of toxic and radioactive metals in the subsurface of uranium tailing pond sites is critical to the assessment of environmental impact and to the development of effective remediation technologies. The mobility of radionuclides and toxic metals is enhanced by acidification of tailings due to sulphide oxidation catalysed by microbial activity. Due to infiltration of water, there is a possibility of leaching of these radionuclides and toxic metals from the tailings pond to the ground water. Sorption onto mineral surfaces is an important mechanism for reducing radionuclide concentrations along ground water flow paths and retarding radionuclide migration to the accessible environment. Reactive transport of ground water contaminants often assume that the reaction governing the retardation of a particular contaminant or radionuclide can be described by simple partitioning constant, K d . This constant is assumed to account for all the reversible sorption processes affecting transport of the contaminant. Experimental determination of site-specific K d values is absolutely essential for the accurate estimation of reactive transport of these contaminants. The results of such studies would be helpful to model migration of these pollutants and to estimate the radiation dose to members of the public through groundwater drinking pathway at different distances from the tailings pond. In the present study it is clearly observed that K d values of most of the radionuclides are strongly dependent on different soil and ground water parameters. The relationships generated between distribution coefficient values of different radionuclides and different soil and ground water parameters can be used to generate look up table. And these relationships can also be used for the prediction of K d values of different radionuclides by using the different physico-chemical parameters of soil and ground water of the particular location

Development of computation model on the GoldSim platform for the radionuclide transport in the geosphere with the time-dependent parameters

International Nuclear Information System (INIS)

Koo, Shigeru; Inagaki, Manabu

2010-06-01

In the high-level radioactive waste (HLW) disposal system, numerical evaluation for radionuclide transport with the time-dependent parameters is necessary to evaluate various scenarios. In H12 report, numerical calculation code MESHNOTE and TIGER were used for the evaluation of some natural phenomena scenarios that had to handle the time-dependent parameters. In the future, the necessity of handling the time-dependent parameters will be expected to increase, and more efficient calculation and improvement of quality control of input/output parameters will be required. Therefore, for the purpose of corresponding this requirement, a radionuclide transport model has been developed on the GoldSim platform. The GoldSim is a general simulation software, that was used for the computation modeling of Yucca Mountain Project. The conceptual model, the mathematical model and the verification of the GoldSim model are described in this report. In the future, application resources on this report will be able to upgrade for perturbation scenarios analysis model and other conceptual models. (author)

Dynamics of radionuclides in forest ecosystems

International Nuclear Information System (INIS)

Steiner, M.

2004-01-01

The unique physiology and the layered structure of forest ecosystems result in dynamic transport and transfer processes which greatly differ from those in agricultural ecosystems. Radionuclides are retained in the upper organic horizons of forest soil for several decades and remain highly available for uptake by fungi and green plants. Contamination levels of mushrooms and game may therefore by far exceed those of agricultural produce. The efficient cycling of nutrients and radionuclides, which is characteristic for ecosystems poor in nutrients, can largely be attributed to forest soil with its complex and multi-layered structure and fungal activity. Fungi directly affect dynamic processes, playing a key role in the mobilization, uptake and translocation of nutrients and radionuclides. Fungal fruit bodies may be highly contaminated foodstuff and fodder. They are most likely the cause of the surprising trend of increasing contamination of wild boar which has been observed in the last few years in Germany. This paper is intended to give a qualitative survey of dynamic transport processes in forests and their relevance for radiation exposure to man. (orig.)

Analysis gives sensibility two models gives migration and transport gives radionuclides in the geosphere

International Nuclear Information System (INIS)

Torres Berdeguez, M. B.; Gil Castillo, R.; Peralta Vidal, J.L.

1998-01-01

An sensibility analysis it was applied two models, the first one, a model compressible for the near field (I finish source) The second, a simple model gives migration and transport radionuclides in the geosphere. The study was developed varying the securities ed simultaneously at the same time each parameter and observing the results in changes in the output and input. The intention in analysis it is to determine the parameter that but it influences in the variation the concentration. The statistical technique Regression it was employee in the study. This statistical method is used to analyze the dependence between a dependent variable and an or but independent variables

Radionuclide content of Las Vegas wash sediments

International Nuclear Information System (INIS)

Rudin, M.J.; Meyers, A.M.; Johnson, W.H.

1996-01-01

The Las Vegas Wash is an excavated waterway channel which drains all surface water and effluent discharge from sewage-treatment facilities from the greater Las Vegas Metropolitan Area to Lake Mead. Runoff and erosion processes are expected to transport man-made radioactivity that was deposited over the past several decades in the Las Vegas Valley. Additionally, radionuclides disposed of via the city's sanitary system are expected to accumulate in the Wash sediments. Fine and coarse sediment samples were collected at 100 m intervals and analyzed to determine the distribution of alpha- and gamma-emitting radionuclides in the lower 5,500 in of the Las Vegas Wash. Results indicate little accumulation of long-lived fission products in upstream Wash sediments. However, trace amounts of fission products measured in downstream sediments suggest the resuspension and transport of radioactive particulate matter within the Wash. Levels of naturally-occurring radionuclides found in Wash sediments were found to be consistent with levels typically found in southeast Nevada soils

Quantitative assessment of radionuclide retention in the near-surface system at Forsmark. Development of a reactive transport model using Forsmark 1.2 data

International Nuclear Information System (INIS)

Grandia, Fidel; Sena, Clara; Arcos, David; Molinero, Jorge; Duro, Lara; Bruno, Jordi

2007-12-01

The main objective of this work is to assess the migration behaviour of selected long-lived radionuclides through the near-surface system of Forsmark, with special focus on the evaluation of the capacity of the Quaternary deposits and sediments for radionuclide retention. The work reported here is based on data and information from Forsmark Site Descriptive Model version 1.2. From the geological point of view, the near-surface systems in the Forsmark area consist of Quaternary deposits and sediments that overlay the granitic bedrock. Glacial till is the more abundant outcropping Quaternary deposit and the remainder is made of clayey deposits. These types of near-surface sediments show distinctive hydraulic and geochemical features. The main reactive mineral in the till deposits, for the time horizons considered in this work, is calcium carbonate together with minor amounts of clay minerals (e.g. illite). The till deposits forms aquifers with relatively high hydraulic conductivities. In contrast, glacial and post-glacial clays are basically composed of illite with low to very low amounts of calcium carbonate, and containing organic matter-rich layers (gyttja), which can promote reducing conditions in the porewaters. All these clays exhibits relatively low hydraulic conductivity values. Five radionuclides have been selected for conceptualization and qualitative evaluation of retention process: U as an actinide, Se as a redox-sensitive radionuclide, Cs as a monovalent cation, Sr as a divalent cation, and I as an anion radionuclide. Overall, radionuclide retention capacity in the surface systems at Forsmark can be provided by sorption on charged surfaces of clays and oxyhydroxides, co-precipitation with sulphates, sulphides, oxyhydroxides and carbonates, and sorption on organic matter. Two-dimensional coupled hydrogeological and reactive solute transport models have been developed to simulate the geochemical behaviour of U, Cs and Sr. These three radionuclides have

Simulating Radionuclide Migrations of Low-level Wastes in Nearshore Environment

Science.gov (United States)

Lu, C. C.; Li, M. H.; Chen, J. S.; Yeh, G. T.

2016-12-01

Tunnel disposal into nearshore mountains was tentatively selected as one of final disposal sites for low-level wastes in Taiwan. Safety assessment on radionuclide migrations in far-filed may involve geosphere processes under coastal environments and into nearshore ocean. In this study the 3-D HYDROFEOCHE5.6 numerical model was used to perform simulations of groundwater flow and radionuclide transport with decay chains. Domain of interest on the surface includes nearby watersheds delineated by digital elevation models and nearshore seabed. As deep as 800 m below the surface and 400 m below sea bed were considered for simulations. The disposal site was located at 200m below the surface. Release rates of radionuclides from near-field was estimated by analytical solutions of radionuclide diffusion with decay out of engineered barriers. Far-field safety assessments were performed starting from the release of radionuclides out of engineered barriers to a time scale of 10,000 years. Sensitivity analyses of geosphere and transport parameters were performed to improve our understanding of safety on final disposal of low-level waste in nearshore environments.

Long-term calculation of radionuclides concentration in the ocean by OGCM

International Nuclear Information System (INIS)

Tsumune, Daisuke; Maruyama, Koki; Nakashiki, Norikazu; Aoyama, Michio; Hirose, Katsumi

2000-01-01

The ocean transports of radioactive materials have been carried out from Europe to Japan through the several routes on the world ocean. To sustain the safety of the transport of radioactive materials and to gain the public acceptance, it is necessary evaluate the radionuclide concentration in the ocean at the hypothetical submergence of radioactive materials into the world ocean. The purpose of this study is to develop a new method to evaluate the radionuclides concentration in the world ocean. A method to calculate the concentration of radionuclides in the ocean was developed using an ocean general circulation model (OGCM). The concentration of radionuclides ( 137 Cs, 90 Sr and 239+240 Pu) in the ocean was calculated from 1957 to 1994, on the assumption that these radionuclides were injected into the ocean only as the fallout from the atmospheric weapons tests. The calculated concentrations gave a good agreement with the observed data. The concentration of radionuclides in the ocean was estimated by this method in case of the hypothetical submergence of a package of fresh MOX fuel into the ocean on the routes of ocean transport from Europe to Japan. We calculated the concentration of 6 radionuclides ( 238 Pu, 239 Pu, 240 Pu, 241 Pu, 242 Pu and 241 Am) over 1000 years. It takes 3.5 CPU hours for 1000-year calculation by the supercomputer HITACHI S3800. The concentration in the ocean due to the hypothetical submergence of a package of fresh MOX fuel is estimated to be much smaller than the present background concentration of fallout. (author)

Quantitative assessment of radionuclide retention in the near-surface system at Forsmark. Development of a reactive transport model using Forsmark 1.2 data

Energy Technology Data Exchange (ETDEWEB)

Grandia, Fidel; Sena, Clara; Arcos, David; Molinero, Jorge; Duro, Lara; Bruno, Jordi (Amphos XXI Consulting S.L., Barcelona (Spain))

2007-12-15

The main objective of this work is to assess the migration behaviour of selected long-lived radionuclides through the near-surface system of Forsmark, with special focus on the evaluation of the capacity of the Quaternary deposits and sediments for radionuclide retention. The work reported here is based on data and information from Forsmark Site Descriptive Model version 1.2. From the geological point of view, the near-surface systems in the Forsmark area consist of Quaternary deposits and sediments that overlay the granitic bedrock. Glacial till is the more abundant outcropping Quaternary deposit and the remainder is made of clayey deposits. These types of near-surface sediments show distinctive hydraulic and geochemical features. The main reactive mineral in the till deposits, for the time horizons considered in this work, is calcium carbonate together with minor amounts of clay minerals (e.g. illite). The till deposits forms aquifers with relatively high hydraulic conductivities. In contrast, glacial and post-glacial clays are basically composed of illite with low to very low amounts of calcium carbonate, and containing organic matter-rich layers (gyttja), which can promote reducing conditions in the porewaters. All these clays exhibits relatively low hydraulic conductivity values. Five radionuclides have been selected for conceptualization and qualitative evaluation of retention process: U as an actinide, Se as a redox-sensitive radionuclide, Cs as a monovalent cation, Sr as a divalent cation, and I as an anion radionuclide. Overall, radionuclide retention capacity in the surface systems at Forsmark can be provided by sorption on charged surfaces of clays and oxyhydroxides, co-precipitation with sulphates, sulphides, oxyhydroxides and carbonates, and sorption on organic matter. Two-dimensional coupled hydrogeological and reactive solute transport models have been developed to simulate the geochemical behaviour of U, Cs and Sr. These three radionuclides have

Introduction to CRRIS: a computerized radiological risk investigation system for assessing atmospheric releases of radionuclides

International Nuclear Information System (INIS)

Baes, C.F. III; Miller, C.W.; Kocher, D.C.; Sjoreen, A.L.; Murphy, B.D.

1985-08-01

The CRRIS is a Computerized Radiological Risk Investigation System consisting of eight fully integrated computer codes which calculate environmental transport of atmospheric releases of radionuclides and resulting doses and health risks to individuals or populations. Each code may also be used alone for various assessment applications. Radionuclides are handled by the CRRIS either in terms of the released radionuclides or the exposure radionuclides which consist of both the released nuclides and decay products that grow in during environmental transport. The CRRIS is not designed to simulate short-term effects. 51 refs

Effect on localized waste-container failure on radionuclide transport from an underground nuclear waste vault

International Nuclear Information System (INIS)

Cheung, S.C.H.; Chan, T.

1983-07-01

In the geological disposal of nuclear fuel waste, one option is to emplace the waste container in a borehole drilled into the floor of the underground vault. In the borehole, the waste container is surrounded by a compacted soil material known as the buffer. A finite-element simulation has been performed to study the effect of localized partial failure of the waste container on the steady-state radionuclide transport by diffusion from the container through the buffer to the surrounding rock and/or backfill. In this study, the radionuclide concentration at the buffer-backfill interface is assumed to be zero. Two cases are considered at the interface between the buffer and the rock. In case 1, a no-flux boundary condition is used to simulate intact rock. In case 2, a constant radionuclide concentration condition is used to simulate fractured rock with groundwater flow. The results show that the effect of localized partial failure of the waste container on the total flux is dependent on the boundary condition at the buffer-rock interface. For the intact rock condition, the total flux is mainly dependent on the location of the failure. The total flux increases as the location changes from the bottom to the top of the emplaced waste container. For a given localized failure of the waste container, the total flux remains unaffected by the area of failed surface below the top of the failure. For fractured rock, the total flux is directly proportional to the failed surface area of the waste container regardless of the failure location

Simplified analytical model to simulate radionuclide release from radioactive waste trenches

International Nuclear Information System (INIS)

Sa, Bernardete Lemes Vieira de

2001-01-01

In order to evaluate postclosure off-site doses from low-level radioactive waste disposal facilities, a computer code was developed to simulate the radionuclide released from waste form, transport through vadose zone and transport in the saturated zone. This paper describes the methodology used to model these process. The radionuclide released from the waste is calculated using a model based on first order kinetics and the transport through porous media was determined using semi-analytical solution of the mass transport equation, considering the limiting case of unidirectional convective transport with three-dimensional dispersion in an isotropic medium. The results obtained in this work were compared with other codes, showing good agreement. (author)

A probabilistic dispersion model applied to the long-range transport of radionuclides from the Chernobyl accident

DEFF Research Database (Denmark)

Lauritzen, B.; Mikkelsen, T.

1999-01-01

Long-range atmospheric transport of radionuclides from the Chernobyl accident is modelled as an Eulerian diffusion process. From observations of the gross deposition pattern of particulate radiocaesium an effective long-range Eddy diffusivity K of the order of 10(6) m(2) s(-1) is inferred....... A corresponding effective deposition length for caesium, R-Cs, defined las the effective distance from Chernobyl to where the aerosols have been deposited, is found to be R-Cs approximate to 1000 km. From the observations of the regional variability of the Chernobyl fallout a simple probabilistic assessment...

Transportation of natural radionuclides and rare earth light elements in the lagoon system of Buena, RJ

International Nuclear Information System (INIS)

Lauria, Dejanira da Costa

1999-03-01

it was investigated the transport of the series natural radionuclides and the earth rare light elements in a coastal lagoon system, located in a monazite rich region, in the coast north region of Rio de Janeiro state. The lagoon water showed off abnormal concentrations of radium isotopes and of the earth rare light elements (ERLEs). The longitudinal gradient of the Ra, of the ERLEs and of the major ion concentration's, whose data were obtained during two and half years of the research at the place, and the statistical analysis pointed to two mainly source as responsible for the water lagoon composition - the marine and the underground waters. The underground water supplies the radionuclides and ERLEs, possibly originated by monazite lixiviation. Based on the water speciation modeling, the results of laboratory adsorption on sediment experiments and the sediment characterization, the behavior of the radio isotopes, the ERLEs, U, Th e Pb-210, along of the lagoon, are discussed. It is also discussed the role of the aquatic macrophyte Typha dominguesis Pers in the nuclide uptake and the following liberation. (author)

Verification and improvement of predictive algorithms for radionuclide migration

International Nuclear Information System (INIS)

Carnahan, C.L.; Miller, C.W.; Remer, J.S.

1984-01-01

This research addresses issues relevant to numerical simulation and prediction of migration of radionuclides in the environment of nuclear waste repositories. Specific issues investigated are the adequacy of current numerical codes in simulating geochemical interactions affecting radionuclide migration, the level of complexity required in chemical algorithms of transport models, and the validity of the constant-k/sub D/ concept in chemical transport modeling. An initial survey of the literature led to the conclusion that existing numerical codes did not encompass the full range of chemical and physical phenomena influential in radionuclide migration. Studies of chemical algorithms have been conducted within the framework of a one-dimensional numerical code that simulates the transport of chemically reacting solutes in a saturated porous medium. The code treats transport by dispersion/diffusion and advection, and equilibrium-controlled proceses of interphase mass transfer, complexation in the aqueous phase, pH variation, and precipitation/dissolution of secondary solids. Irreversible, time-dependent dissolution of solid phases during transport can be treated. Mass action, transport, and sorptive site constraint equations are expressed in differential/algebraic form and are solved simultaneously. Simulations using the code show that use of the constant-k/sub D/ concept can produce unreliable results in geochemical transport modeling. Applications to a field test and laboratory analogs of a nuclear waste repository indicate that a thermodynamically based simulator of chemical transport can successfully mimic real processes provided that operative chemical mechanisms and associated data have been correctly identified and measured, and have been incorporated in the simulator. 17 references, 10 figures

PRESTO-II: a low-level waste environmental transport and risk assessment code

International Nuclear Information System (INIS)

Fields, D.E.; Emerson, C.J.; Chester, R.O.; Little, C.A.; Hiromoto, G.

1986-04-01

PRESTO-II (Prediction of Radiation Effects from Shallow Trench Operations) is a computer code designed for the evaluation of possible health effects from shallow-land and, waste-disposal trenches. The model is intended to serve as a non-site-specific screening model for assessing radionuclide transport, ensuing exposure, and health impacts to a static local population for a 1000-year period following the end of disposal operations. Human exposure scenarios considered include normal releases (including leaching and operational spillage), human intrusion, and limited site farming or reclamation. Pathways and processes of transit from the trench to an individual or population include ground-water transport, overland flow, erosion, surface water dilution, suspension, atmospheric transport, deposition, inhalation, external exposure, and ingestion of contaminated beef, milk, crops, and water. Both population doses and individual doses, as well as doses to the intruder and farmer, may be calculated. Cumulative health effects in terms of cancer deaths are calculated for the population over the 1000-year period using a life-table approach. Data are included for three example sites: Barnwell, South Carolina; Beatty, Nevada; and West Valley, New York. A code listing and example input for each of the three sites are included in the appendices to this report

PRESTO-II: a low-level waste environmental transport and risk assessment code

Energy Technology Data Exchange (ETDEWEB)

Fields, D.E.; Emerson, C.J.; Chester, R.O.; Little, C.A.; Hiromoto, G.

1986-04-01

PRESTO-II (Prediction of Radiation Effects from Shallow Trench Operations) is a computer code designed for the evaluation of possible health effects from shallow-land and, waste-disposal trenches. The model is intended to serve as a non-site-specific screening model for assessing radionuclide transport, ensuing exposure, and health impacts to a static local population for a 1000-year period following the end of disposal operations. Human exposure scenarios considered include normal releases (including leaching and operational spillage), human intrusion, and limited site farming or reclamation. Pathways and processes of transit from the trench to an individual or population include ground-water transport, overland flow, erosion, surface water dilution, suspension, atmospheric transport, deposition, inhalation, external exposure, and ingestion of contaminated beef, milk, crops, and water. Both population doses and individual doses, as well as doses to the intruder and farmer, may be calculated. Cumulative health effects in terms of cancer deaths are calculated for the population over the 1000-year period using a life-table approach. Data are included for three example sites: Barnwell, South Carolina; Beatty, Nevada; and West Valley, New York. A code listing and example input for each of the three sites are included in the appendices to this report.

Radionuclide Sensors for Water Monitoring

International Nuclear Information System (INIS)

Grate, Jay W.; Egorov, Oleg B.; DeVol, Timothy A.

2004-01-01

Radionuclide contamination in the soil and groundwater at U.S. Department of Energy (DOE) sites is a severe problem that requires monitoring and remediation. Radionuclide measurement techniques are needed to monitor surface waters, groundwater, and process waters. Typically, water samples are collected and transported to an analytical laboratory, where costly radiochemical analyses are performed. To date, there has been very little development of selective radionuclide sensors for alpha- and beta-emitting radionuclides such as 90Sr, 99Tc, and various actinides of interest. The objective of this project is to investigate novel sensor concepts and materials for sensitive and selective determination of beta- and alpha-emitting radionuclide contaminants in water. To meet the requirements for loW--level, isotope-specific detection, the proposed sensors are based on radiometric detection. As a means to address the fundamental challenge of the short ranges of beta and alpha particle s in water, our overall approach is based on localization of preconcentration/separation chemistries directly on or within the active area of a radioactivity detector. Automated microfluidics is used for sample manipulation and sensor regeneration or renewal. The outcome of these investigations will be the knowledge necessary to choose appropriate chemistries for selective preconcentration of radionuclides from environmental samples, new materials that combine chemical selectivity with scintillating properties, new materials that add chemical selectivity to solid-state diode detectors, new preconcentrating column sensors, and improved instrumentation and signal processing for selective radionuclide sensors. New knowledge will provide the basis for designing effective probes and instrumentation for field and in situ measurements

A new statistical method for transfer coefficient calculations in the framework of the general multiple-compartment model of transport for radionuclides in biological systems.

Science.gov (United States)

Garcia, F; Arruda-Neto, J D; Manso, M V; Helene, O M; Vanin, V R; Rodriguez, O; Mesa, J; Likhachev, V P; Filho, J W; Deppman, A; Perez, G; Guzman, F; de Camargo, S P

1999-10-01

A new and simple statistical procedure (STATFLUX) for the calculation of transfer coefficients of radionuclide transport to animals and plants is proposed. The method is based on the general multiple-compartment model, which uses a system of linear equations involving geometrical volume considerations. By using experimentally available curves of radionuclide concentrations versus time, for each animal compartment (organs), flow parameters were estimated by employing a least-squares procedure, whose consistency is tested. Some numerical results are presented in order to compare the STATFLUX transfer coefficients with those from other works and experimental data.

A new statistical method for transfer coefficient calculations in the framework of the general multiple-compartment model of transport for radionuclides in biological systems

International Nuclear Information System (INIS)

Garcia, F.; Manso, M.V.; Rodriguez, O.; Mesa, J.; Arruda-Neto, J.D.T.; Helene, O.M.; Vanin, V.R.; Likhachev, V.P.; Pereira Filho, J.W.; Deppman, A.; Perez, G.; Guzman, F.; Camargo, S.P. de

1999-01-01

A new and simple statistical procedure (STATFLUX) for the calculation of transfer coefficients of radionuclide transport to animals and plants is proposed. The method is based on the general multiple-compartment model, which uses a system of linear equations involving geometrical volume considerations. By using experimentally available curves of radionuclide concentrations versus time, for each animal compartment (organs), flow parameters were estimated by employing a least-squares procedure, whose consistency is tested. Some numerical results are presented in order to compare the STATFLUX transfer coefficients with those from other works and experimental data. (author)

Hydrology and radionuclide migration program 1987 progress report

International Nuclear Information System (INIS)

Marsh, K.V.

1991-03-01

This report presents results from the Lawrence Livermore National Laboratory's participation in the Hydrology and Radionuclide Migration Program at the Nevada Test Site (NTS) during the fiscal year 1987. The report discussed initial data from a new well (UE20n-1) drilled at the Cheshire site; presents a description of a proposed laboratory study of migration of colloids in fractured media; lists data collected during the drilling and initial sampling of UE20n-1; and describes a tentative proposal for work to be performed in FY88 by Lamont-Doherty Geological Observatory. Groundwater sampled from the new well at the Cheshire site contains tritium concentrations comparable to those measured in previous years from locations above and within the Cheshire cavity. This presence of tritium, as well as several other radionuclides, in a well 100 m away from the cavity region indicates transport of radionuclides, validates a proposed model of the flow path, and provides data on rates of groundwater flow. Previous work at the Cheshire site has shown that radionuclides are transported by colloids through fractured media. However, we have no data that can be used for predictive modeling, and existing theories are not applicable. While physical transport mechanisms of sub-micrometer colloids to defined mineral surfaces are well known, predictions based on well-defined conditions differ from experimental observations by orders of magnitude. The U.C. Berkeley group has designed a laboratory experiment to quantify colloid retention and permeability alteration by the retained colloids

A basic toxicity classification of radionuclides

International Nuclear Information System (INIS)

1963-01-01

In the course of its work in the field of health and safety the International Atomic Energy Agency has often met the practical requirement for grading radionuclides in order of their relative radiotoxicities. This need was particularly evident when the Agency's Basic Safety Standards for the protection of health against ionizing radiation were in preparation, when it was necessary to exempt quantities of radionuclides from inclusion in the norms. A basic toxicity grading might be of help to laboratories in meeting some of their requirements in problems related to waste management as well as for the design of experimental facilities. It should also serve as a basis for the development of safety criteria for laboratory equipment and procedures for handling and transporting various quantities and kinds of radionuclides. The purpose of the present Report is to make a toxicity grading of the radionuclides according to the risk of biological injury which they may cause when they have become incorporated in the human body. 4 refs, 4 tabs

A basic toxicity classification of radionuclides

Energy Technology Data Exchange (ETDEWEB)

1963-04-01

In the course of its work in the field of health and safety the International Atomic Energy Agency has often met the practical requirement for grading radionuclides in order of their relative radiotoxicities. This need was particularly evident when the Agency's Basic Safety Standards for the protection of health against ionizing radiation were in preparation, when it was necessary to exempt quantities of radionuclides from inclusion in the norms. A basic toxicity grading might be of help to laboratories in meeting some of their requirements in problems related to waste management as well as for the design of experimental facilities. It should also serve as a basis for the development of safety criteria for laboratory equipment and procedures for handling and transporting various quantities and kinds of radionuclides. The purpose of the present Report is to make a toxicity grading of the radionuclides according to the risk of biological injury which they may cause when they have become incorporated in the human body. 4 refs, 4 tabs.

Chemistry of groundwater and the migration process of radionuclides

International Nuclear Information System (INIS)

Olteanu, Mirela; Popa, Aurelia; Crina, Bucur

2001-01-01

Establishing the criteria of selection of a host site for final repository of low and intermediate radioactive waste is based upon the study of two major components, the radioactivity diffusion in disposal site and the environmental impact. The hydrological characteristics of geological formation are the main factors that control radionuclides moving (migration), because, in general, the water is the natural way for dissolving and transport of these in environment. In interaction of the water with environment, the water is present like a dynamic and complex system, which contents dissolved or suspension of mineral and organic substances. Knowing the water-soil system interaction mechanism, the physical-chemical characteristics of each component in this system, the mobility in time of radionuclides, from the repository in environment can be estimated. In migration, the main problem is determination of transport rate of radionuclides in environment. (authors)

Biosphere transport of radionuclides. First modelling by using a selected example

International Nuclear Information System (INIS)

Bundi, A.

1984-12-01

The dispersion of radionuclides in the biosphere and their uptake by man via various nutritional pathways is studied using a compartment model. The sample environment is the area of the lower Limmat and Aare valleys. General considerations of the compartmental description of the biosphere are made. The problem of the description of surface features, in particular soil, sediment and water, is studied in detail using the code BIOPATH. This study is intended to be an example of how a model of the biosphere could be constructed. It is shown that this is a reasonable model to calculate the spreading of radionuclides in the biosphere and that it indicates the relative significance of individual compartments, pathways and radionuclides. Calculated values of doses to man, however, should not be used as reference data for safety analyses. (author)

Comparison of one-, two-, and three-dimensional models for mass transport of radionuclides

International Nuclear Information System (INIS)

Prickett, T.A.; Voorhees, M.L.; Herzog, B.L.

1980-02-01

This technical memorandum compares one-, two-, and three-dimensional models for studying regional mass transport of radionuclides in groundwater associated with deep repository disposal of high-level radioactive wastes. In addition, this report outlines the general conditions for which a one- or two-dimensional model could be used as an alternate to a three-dimensional model analysis. The investigation includes a review of analytical and numerical models in addition to consideration of such conditions as rock and fluid heterogeneity, anisotropy, boundary and initial conditions, and various geometric shapes of repository sources and sinks. Based upon current hydrologic practice, each review is taken separately and discussed to the extent that the researcher can match his problem conditions with the minimum number of model dimensions necessary for an accurate solution

Simulation of radionuclide retardation at Yucca Mountain using a stochastic mineralogical/geochemical model

International Nuclear Information System (INIS)

Birdsell, K.H.; Campbell, K.; Eggert, K.; Travis, B.J.

1990-01-01

This paper presents preliminary transport calculations for radionuclide movement at Yucca Mountain. Several different realizations of spatially distributed sorption coefficients are used to study the sensitivity of radionuclide migration. These sorption coefficients are assumed to be functions of the mineralogic assemblages of the underlying rock. The simulations were run with TRACRN 1 , a finite-difference porous flow and radionuclide transport code developed for the Yucca Mountain Project. Approximately 30,000 nodes are used to represent the unsaturated and saturated zones underlying the repository in three dimensions. Transport calculations for a representative radionuclide cation, 135 Cs, and anion, 99 Tc, are presented. Calculations such as these will be used to study the effectiveness of the site's geochemical barriers at a mechanistic level and to help guide the geochemical site characterization program. The preliminary calculations should be viewed as a demonstration of the modeling methodology rather than as a study of the effectiveness of the geochemical barriers. The model provides a method for examining the integration of flow scenarios with transport and retardation processes as currently understood for the site. The effects on transport of many of the processes thought to be active at Yucca Mountain may be examined using this approach. 11 refs., 14 figs., 1 tab

Influence of speciation on the geospheric migration of radionuclides

International Nuclear Information System (INIS)

Hadermann, J.; Schweingruber, M.

1982-01-01

For geosphere transport calculations in safety analyses of waste repositories it is generally assumed that the retardation of a migrating radionuclide is characterized by a single retention factor. However, in groundwater, radionuclides exist in various chemical forms with strongly differing sorption properties. We consider the effect of pseudo first order chemical reactions in liquid phase on migration. Conditions are derived under which local equilibrium in liquid phase is well fulfilled and migration is governed by a single effective retention factor. It is argued that in geosphere transport, equilibrium is likely to exist even when laboratory measurements show chromatographic separations. (author)

Radionuclide transport and dose assessment modelling in biosphere assessment 2009

International Nuclear Information System (INIS)

Hjerpe, T.; Broed, R.

2010-11-01

Following the guidelines set forth by the Ministry of Trade and Industry (now Ministry of Employment and Economy), Posiva is preparing to submit a construction license application for the final disposal spent nuclear fuel at the Olkiluoto site, Finland, by the end of the year 2012. Disposal will take place in a geological repository implemented according to the KBS-3 method. The long-term safety section supporting the license application will be based on a safety case that, according to the internationally adopted definition, will be a compilation of the evidence, analyses and arguments that quantify and substantiate the safety and the level of expert confidence in the safety of the planned repository. This report documents in detail the conceptual and mathematical models and key data used in the landscape model set-up, radionuclide transport modelling, and radiological consequences analysis applied in the 2009 biosphere assessment. Resulting environmental activity concentrations in landscape model due to constant unit geosphere release rates, and the corresponding annual doses, are also calculated and presented in this report. This provides the basis for understanding the behaviour of the applied landscape model and subsequent dose calculations. (orig.)

Impact of kinetics and flow path heterogeneity on nanoparticle/radionuclide migration

International Nuclear Information System (INIS)

Huber, Florian M.

2011-01-01

The prevailing PhD thesis experimentally investigates the impact of both sorption/desorption (reversibility) and reduction kinetics on radionuclide migration in synthetic and natural systems from the nano-to the centimeter scale. Furthermore, the impact of fracture heterogeneity on flow and solute/nanoparticle transport as a potential additional retardation mechanism is examined both on an experimental and numerical basis. The process of sorptive reduction of U(VI) to sparingly soluble tetravalent uranium by structural bound Fe(II) in magnetite shows fast kinetics (hours to a few days contact time). A clear correlation between the Fe(II) content on the magnetite surface and the amount of U(VI) was observed, that is, increasing U(IV) with increasing Fe(II). Moreover, a congruency between the measured Eh(SHE) and the U valence state can partly been derived within the analytical uncertainties of the redox potential measurements. Thus, secondary phases as the stainless steel corrosion product magnetite can have beneficial effects on radionuclide migration as an effective retardation pathway for redox sensitive radionuclides. Beside, the studies on U(VI) maghemite sorption show that oxidized surfaces can possess long-term reduction capacities further enhancing radionuclide retention. Concerning the colloid-facilitated radionuclide transport, the batch sorption reversibility studies revealed the significance of kinetically controlled radionuclide desorption from the colloidal phase and subsequent sorption to the fracture filling materials (independent of the mineralogy and/or size fraction). By this process, initially colloidal associated radionuclides like the tri-and tetravalent radionuclides Th, Pu and Am are effectively retarded leading to an increase in the residence time. These reversibility results need to be included in codes for simulating colloid-facilitated radionuclide transport to reduce the conservatism and degree of uncertainties in input parameters

Impact of kinetics and flow path heterogeneity on nanoparticle/radionuclide migration

Energy Technology Data Exchange (ETDEWEB)

Huber, Florian M.

2011-11-29

The prevailing PhD thesis experimentally investigates the impact of both sorption/desorption (reversibility) and reduction kinetics on radionuclide migration in synthetic and natural systems from the nano-to the centimeter scale. Furthermore, the impact of fracture heterogeneity on flow and solute/nanoparticle transport as a potential additional retardation mechanism is examined both on an experimental and numerical basis. The process of sorptive reduction of U(VI) to sparingly soluble tetravalent uranium by structural bound Fe(II) in magnetite shows fast kinetics (hours to a few days contact time). A clear correlation between the Fe(II) content on the magnetite surface and the amount of U(VI) was observed, that is, increasing U(IV) with increasing Fe(II). Moreover, a congruency between the measured Eh(SHE) and the U valence state can partly been derived within the analytical uncertainties of the redox potential measurements. Thus, secondary phases as the stainless steel corrosion product magnetite can have beneficial effects on radionuclide migration as an effective retardation pathway for redox sensitive radionuclides. Beside, the studies on U(VI) maghemite sorption show that oxidized surfaces can possess long-term reduction capacities further enhancing radionuclide retention. Concerning the colloid-facilitated radionuclide transport, the batch sorption reversibility studies revealed the significance of kinetically controlled radionuclide desorption from the colloidal phase and subsequent sorption to the fracture filling materials (independent of the mineralogy and/or size fraction). By this process, initially colloidal associated radionuclides like the tri-and tetravalent radionuclides Th, Pu and Am are effectively retarded leading to an increase in the residence time. These reversibility results need to be included in codes for simulating colloid-facilitated radionuclide transport to reduce the conservatism and degree of uncertainties in input parameters

The behaviour of radionuclides in soil

International Nuclear Information System (INIS)

Bunzl, K.

1987-01-01

Radionuclides in soil are of natural as well as of artificial origin. Their migration in the soil and their availability for ecological processes depend considerably on the extent at which they are sorbed. The methods for the determination of the vertical rate of migration are described. For most radionuclides this transport is very slow (a few cm per year). Cs-137 is of especial interest. It is sorbed strongly by most soils and, as a consequence, its root uptake is small. However, as a result of the sorption, this radionuclide is eluted from the root zone only very slowly and its thus available for the root uptake for many years. The Cs-137 concentrations in plants to be expected in the coming years as a result of the fallout from Chernobyl are small. (orig.) [de

Modelling of radionuclide migration and heat transport from an High-Level-Radioactive-Waste-repository (HLW) in Boom clay

International Nuclear Information System (INIS)

Put, M.; Henrion, P.

1992-01-01

For the modelling of the migration of radionuclides in the Boom clay formation, the analytical code MICOF has been updated with a 3-dimensional analytical solution for discrete sources. the MICOF program is used for the calculation of the release of α and β emitters from the HIGH LEVEL RADIOACTIVE WASTES (HLW). A coherent conceptual model is developed which describes all the major physico-chemical phenomena influencing the migration of radionuclides in the Boom clay. The concept of the diffusion accessible porosity is introduced and included in the MICOF code. Different types of migration experiments are described with their advantages and disadvantages. The thermal impact of the HLW disposal in the stratified Boom clay formation has been evaluated by a finite element simulation of the coupled heat and mass transport equation. The results of the simulations show that under certain conditions thermal convection cells may form, but the convective heat transfer in the clay formation is negligible. 6 refs., 19 figs., 2 tabs., 5 appendices

Modeling of radionuclide transport through rock formations and the resulting radiation exposure of reference persons. Calculations using Asse II parameters; Modellierung des Transports von Radionukliden durch Gesteinsschichten und der resultierenden Strahlenexposition von Referenzpersonen. Berechnungen mit Parametern der Asse II

Energy Technology Data Exchange (ETDEWEB)

Kueppers, Christian; Ustohalova, Veronika; Steinhoff, Mathias

2012-05-21

The long-term release of radioactivity into the ground water path cannot be excluded for the radioactive waste repository Asse II. The possible radiological consequences were analyzed using a radio-ecological scenario developed by GRS. A second scenario was developed considering the solubility of radionuclides in salt saturated solutions and retarding/retention effects during the radionuclide transport through the cap rock layers. The modeling of possible radiation exposure was based on the lifestyle habits of reference persons. In Germany the calculation procedure for the prediction of radionuclide release from final repositories is not defined by national standards, the used procedures are based on analogue methods from other radiation protection calculations.

BLT-EC (Breach, Leach Transport, and Equilibrium Chemistry), a finite-element model for assessing the release of radionuclides from low-level waste disposal units: Background, theory, and model description

International Nuclear Information System (INIS)

MacKinnon, R.J.; Sullivan, T.M.; Simonson, S.A.; Suen, C.J.

1995-08-01

Performance assessment models typically account for the processes of sorption and dissolution-precipitation by using an empirical distribution coefficient, commonly referred to as K d that combines the effects of all chemical reactions between solid and aqueous phases. In recent years, however, there has been an increasing awareness that performance assessments based solely on empirically based K d models may be incomplete, particularly for applications involving radionuclides having sorption and solubility properties that are sensitive to variations in the in-situ chemical environment. To accommodate variations in the in-situ chemical environment, and to assess its impact on radionuclide mobility, it is necessary to model radionuclide release, transport, and chemical processes in a coupled fashion. This modeling has been done and incorporated into the two-dimensional, finite-element, computer code BLT-EC (Breach, Leach, Transport, Equilibrium Chemistry). BLT-EC is capable of predicting container degradation, waste-form leaching, and advective-dispersive, multispecies, solute transport. BLT-EC accounts for retardation directly by modeling the chemical processes of complexation, sorption, dissolution-precipitation, ion-exchange, and oxidation-reduction reactions. In this report we: (1) present a detailed description of the various physical and chemical processes that control the release and migration of radionuclides from shallow land LLW disposal facilities; (2) formulate the mathematical models that represent these processes; (3) outline how these models are incorporated and implemented in BLT-EC; and (4) demonstrate the application of BLT-EC on a set of example problems

The reactor accident at Chernobyl: A possibility to test colloid-controlled transport of radionuclides

International Nuclear Information System (INIS)

Von Gunten, H.R.; Waber, U.; Krahenbuhl, U.

1987-01-01

Radioactive fall-out from the damaged nuclear power plant at Chernobyl (USSR) has been measured between May 2 and May 20, 1986 in the River Glatt (Zurich, Switzerland) and in a shallow groundwater stream which is hydraulically connected to the river. Water infiltrating from the river into the groundwater was sampled at different distances and depths by means of a system of piezometer tubes which are part of an experimental installation for the investigation of groundwater quality and migration processes. The aquifer is a quarternary glaciofluvial deposit consisting of stones, gravel, sand, silt and clays. It is typical for large parts of alpine and peri-alpine regions and contains in Switzerlamd about 80% of the drinking water supplies. The radionuclides Tc-99m, Ru-103, I-131, Te-132, Cs-134 and Cs-137 were measured several times in the river water and in the groundwater using calibrated Ge(Li) gamma-ray spectrometers. Based on the present state of data evaluation the authors conclude that anionic species like iodides, ruthenates or tellurates are not or only slightly sorbed, whereas cesium is completely retained during infiltration from the river into the groundwater. Colloid (>0.05 μm) controlled migration of radionuclides in this heterogeneous glaciofluvial deposits is a transport mechanism of minor importance. However, with the present data it cannot be excluded completely

Initial Radionuclide Inventories

Energy Technology Data Exchange (ETDEWEB)

H. Miller

2004-09-19

The purpose of this analysis is to provide an initial radionuclide inventory (in grams per waste package) and associated uncertainty distributions for use in the Total System Performance Assessment for the License Application (TSPA-LA) in support of the license application for the repository at Yucca Mountain, Nevada. This document is intended for use in postclosure analysis only. Bounding waste stream information and data were collected that capture probable limits. For commercially generated waste, this analysis considers alternative waste stream projections to bound the characteristics of wastes likely to be encountered using arrival scenarios that potentially impact the commercial spent nuclear fuel (CSNF) waste stream. For TSPA-LA, this radionuclide inventory analysis considers U.S. Department of Energy (DOE) high-level radioactive waste (DHLW) glass and two types of spent nuclear fuel (SNF): CSNF and DOE-owned (DSNF). These wastes are placed in two groups of waste packages: the CSNF waste package and the codisposal waste package (CDSP), which are designated to contain DHLW glass and DSNF, or DHLW glass only. The radionuclide inventory for naval SNF is provided separately in the classified ''Naval Nuclear Propulsion Program Technical Support Document'' for the License Application. As noted previously, the radionuclide inventory data presented here is intended only for TSPA-LA postclosure calculations. It is not applicable to preclosure safety calculations. Safe storage, transportation, and ultimate disposal of these wastes require safety analyses to support the design and licensing of repository equipment and facilities. These analyses will require radionuclide inventories to represent the radioactive source term that must be accommodated during handling, storage and disposition of these wastes. This analysis uses the best available information to identify the radionuclide inventory that is expected at the last year of last emplacement

Hydrology and radionuclide migration program 1987 progress report

Energy Technology Data Exchange (ETDEWEB)

Marsh, K.V. (comp.)

1991-03-01

This report presents results from the Lawrence Livermore National Laboratory's participation in the Hydrology and Radionuclide Migration Program at the Nevada Test Site (NTS) during the fiscal year 1987. The report discussed initial data from a new well (UE20n-1) drilled at the Cheshire site; presents a description of a proposed laboratory study of migration of colloids in fractured media; lists data collected during the drilling and initial sampling of UE20n-1; and describes a tentative proposal for work to be performed in FY88 by Lamont-Doherty Geological Observatory. Groundwater sampled from the new well at the Cheshire site contains tritium concentrations comparable to those measured in previous years from locations above and within the Cheshire cavity. This presence of tritium, as well as several other radionuclides, in a well 100 m away from the cavity region indicates transport of radionuclides, validates a proposed model of the flow path, and provides data on rates of groundwater flow. Previous work at the Cheshire site has shown that radionuclides are transported by colloids through fractured media. However, we have no data that can be used for predictive modeling, and existing theories are not applicable. While physical transport mechanisms of sub-micrometer colloids to defined mineral surfaces are well known, predictions based on well-defined conditions differ from experimental observations by orders of magnitude. The U.C. Berkeley group has designed a laboratory experiment to quantify colloid retention and permeability alteration by the retained colloids.

Particles and solutes migration in porous medium : radionuclides and clayey particles simultaneous transport under the effect of a salinity gradient

International Nuclear Information System (INIS)

Faure, M.H.

1994-01-01

This work deals with the radiation protection of high-level and long-life radioactive waste storages. The colloids presence in ground waters can accelerate the radionuclides migration in natural geological deposits. The aim of this thesis is then to control particularly the particles motion in porous medium in order to anticipate quantitatively their migration. Liquid chromatography columns are filled with a clayey sand and fed with a decreasing concentration sodium chloride solution in order to study the particles outlet under a salinity gradient. When the porous medium undergoes a decrease of salinity it deteriorates. The adsorption of the cations : sodium 22, calcium 45, cesium 137 and neptunium 237 is then studied by the ions exchange method. The radionuclide solution is injected before the decrease of the feed solution salinity. The decrease of the sodium chloride concentration leads to the decrease of the radionuclides concentration because the adsorption competition between the sodium ion and the injected cation is lower. The particles transport, without fouling of the porous medium, is carried out in particular physical and chemical conditions which are described. (O.L.). 71 refs., 105 figs., 26 tabs

Parameter-sensitivity analysis of near-field radionuclide transport in buffer material and rock for an underground nuclear fuel waste vault

International Nuclear Information System (INIS)

Cheung, S.C.H.; Chan, T.

1983-08-01

An analytical model has been developed for radionuclide transport in the vicinity of a nuclear fuel waste container emplaced in a borehole. The model considers diffusion in the buffer surrounding the waste container, and both diffusion and groundwater convection in the rock around the borehole. A parameter-sensitivity analysis has been done to study the effects on radionuclide flux of (a) Darcian velocity of groundwater in the rock, (b) effective porosity of the buffer, (c) porosity of the rock, (d) radial buffer thickness, and (e) radius and length of the container. It is found that the radionuclide flux, Fsub(R), and the total integrated flux, Fsub(T), are greater for horizontal flow than for vertical flow; Fsub(R) decreases with increasing radial buffer thickness for all Darcian velocities, whereas Fsub(T) decreases at high velocities but increases at low velocities. The rate of change of Fsub(R) and of Fsub(T) decreases with decreasing flow velocity and increasing buffer thickness; Fsub(R) is greater for higher effective porosity of buffer or rock; and Fsub(R) increases and Fsub(T) decreases with decreasing container radius or length

A review of radionuclide release and transport in recent in-pile experiments

International Nuclear Information System (INIS)

Harman, N.F.; Clough, P.N.

1992-01-01

The experimental series, reviewed in this work, are LOFT-LP-FP-2, PBF SFD ST to 1-4, Treat/STEP I to 4, and ACRR ST-1 and ST-2. These have the common features of in-core heating of a test fuel bundle to high temperatures (usually with some fuel melting) in an experimental reactor core, and of collecting and analysing the released fission products. They were designed to provide detailed information on the release from fuel of fission products and other radionuclides under LWR severe accident conditions, and on the chemical and physical forms and transport of the fission products. The main aim of this review is to bring together, in a systematic way, information on the conduct of the tests, on their successes and failures, and particularly on the information they generated on the chemical and physical behaviour of released fission products. By examining and analysing the data from all of the tests together, patterns of fission product behaviour may become apparent and insights may be gained, which would not be arrived at from individual test results. Moreover, important lessons may be learned, and useful guidance obtained, relating to the aims and conduct of future experimental programmes of fission product release from fuel and transport behaviour. The conclusions should be particularly relevant to the imminent Phebus-FP in-pile test series at Cadarache

Radionuclide co-precipitation

International Nuclear Information System (INIS)

Bruno, J.; Sandino, A.

1987-12-01

The thermodynamic and kinetic behaviour of the minor components of the spent fuel matrix has been theoretically and experimentally investigated. Two different situations have been studied: Part I, the near field scenario, where the release and migration of the minor components is dependent on the solubility behaviour of UO 2 (s); Part II, the far field, where the solubility and transport of the radionuclides is related to the major geochemical processes occurring. (orig.)

Use of MICRAS code on the evaluation of the maximum radionuclides concentrations due to transport/migration of decay chain in groundwaters

International Nuclear Information System (INIS)

Aquino Branco, O.E. de

1995-01-01

This paper presents a methodology for the evaluation of the maximum radionuclides concentrations in groundwaters, due to the transport/migration of decay chains. Analytical solution of the equations system is difficult, even if only three elements of the decay chain are considered. Therefore, a numerical solution is most convenient. An application of the MICRAS code, developed to assess maximum concentrations of each radionuclide, starting with the initial concentrations, is presented. The maximum concentration profile for 226 Ra, calculated using MICRAS, is compared with the results obtained through an analytical and a numerical model. The fitness of results is considered good. Simplified models, like the one represented by the application of MICRAS, are largely employed in the section in the selection and characterization of sites for radioactive wastes repositories and in studies of safety evaluation for the same purpose. A detailed analysis of the transport/migration of contaminants in aquifers requires a large quantify of data from the site and from the installation as well, which makes this analysis expensive and inviable during the preliminary phases of the studies. (author). 6 refs, 1 fig, 1 tab

Transport and deposition of particles and radionuclides at the Puy de Dome, France

International Nuclear Information System (INIS)

Bourcier, L.

2009-01-01

Aerosol particles play a key role both on air quality and on the radiative balance of the Earth. Their sources, as well as their deposition are key stages in their life cycle. This work is a contribution in a better knowledge of the chemical composition of particles, cloud droplets and rain droplets. The specificity of our study is to couple, on three sampling sites (Puy de Dome (1465 m a.s.l.), Opme (660 m a.s.l.) and Cezeaux (400 m a.s.l.)), observations on the chemical composition and the radionuclides activity in cloud/rain/aerosol phases. We observed, in aerosol phase, ionic and carbonaceous concentrations and radionuclides activity higher in summer than in winter at the Puy de Dome, inverse of the seasonal variation observed at the Cezeaux for chemical compounds. From these observations, we offer a representative composition de each mass air type. This work is supplemented by a study of cloud and rain liquid, which allow us to study the scavenging of the pollutants by the rain. The chemical composition of the rain reveals a similar behaviour to that of the particles at the Puy de Dome, indicating that the role of activation and scavenging of particles is preponderant in the composition of the rain. This is confirmed by a study of the environmental and structural factors of the rain which do not seem to influence the washout ratio in a significant manner. Our work highlights the role of long range transport of pollutants in the composition of atmospheric liquid phase. (author)

Transport and accumulation of radionuclides and stable elements in a Missouri River reservoir

International Nuclear Information System (INIS)

Callender, E.; Robbins, J.A.

1993-01-01

Several long sediment cores from the Cheyenne River Embayment of Lake Oahe, a 250-km-long Missouri River reservoir in South Dakota, have been analyzed for radionuclides and stable elements. The combination of fine-scale sampling and rapid sedimentation produces radionuclide distributions that can be used to estimate the detailed chronology of particle transport processes in the Oahe reservoir system. A self-consistent and quantitative treatment of the Cesium 137 data suggests processes to which characteristic times may be associated. Times that characterize system-wide processes include (1) an integration time of several years reflecting retention of the sediment-bound tracer in regions within or external to the reservoir, (2) a relaxation time of approximately 15 years reflecting a decreasing rate of sediment accumulation ascribed to shoreline stabilization, (3) a time of a few months characterizing the breadth of riverine signatures in cores due to integration effects in the Cheyenne River system and deltaic deposits, and (4) times of a few years associated with propagation of riverine load signatures along the embayment. The distribution of total sedimentary arsenic confirms the validity of the variable sedimentation model. In 1977, a tailings retention facility was built at the Homestake Mine site, and the unrestricted input of As ceased. As a result of this remedial action, the concentration of sedimentary As decreased dramatically. Because there is minimal diagenesis of chemical constituents in the rapidly accumulating sediments, stable element signatures, in addition to radiotracers, may be used to reconstruct hydrologic events in drainage basins that contribute sediment to lakes and reservoirs

The fate and importance of radionuclides produced in nuclear events

Energy Technology Data Exchange (ETDEWEB)

Shore, B; Anspaugh, L; Chertok, R; Gofman, J; Harrison, F; Heft, R; Koranda, J; Ng, Y; Phelps, P; Potter, G; Tamplin, A [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

1969-07-01

Some of the major program at the Bio-Medical Division concerned with the fate and importance of the fission products, the radionuclides induced in the device materials, the radionuclides induced in the environment surrounding the device, and the tritium produced in Plowshare cratering events will be discussed. These programs include (1) critical unknowns in predicting organ and body burdens from radionuclides produced in cratering events; (2) the analysis with a high-resolution solid state gamma ray spectrometer of radionuclides in complex biological and environmental samples; (3) the characterization of radioactive particles from cratering detonation; (4) the biological availability to beagles, pigs and goats of radionuclides in Plowshare debris; (5) the biological availability to aquatic animals of radionuclides in Plowshare and other nuclear debris and the biological turnover of critical nuclides in specific aquatic animals; (6) the biological availability of Plowshare and other nuclear debris radionuclides to dairy cows and the transplacental transport of debris radionuclides in the dairy cow; (7) the persistence and behavior of radionuclides, particularly tritium, at sites of Plowshare and other nuclear detonations; and (8) somatic effects of Low Dose Radiation: Chromosome studies. (author)

The fate and importance of radionuclides produced in nuclear events

International Nuclear Information System (INIS)

Shore, B.; Anspaugh, L.; Chertok, R.; Gofman, J.; Harrison, F.; Heft, R.; Koranda, J.; Ng, Y.; Phelps, P.; Potter, G.; Tamplin, A.

1969-01-01

Some of the major program at the Bio-Medical Division concerned with the fate and importance of the fission products, the radionuclides induced in the device materials, the radionuclides induced in the environment surrounding the device, and the tritium produced in Plowshare cratering events will be discussed. These programs include (1) critical unknowns in predicting organ and body burdens from radionuclides produced in cratering events; (2) the analysis with a high-resolution solid state gamma ray spectrometer of radionuclides in complex biological and environmental samples; (3) the characterization of radioactive particles from cratering detonation; (4) the biological availability to beagles, pigs and goats of radionuclides in Plowshare debris; (5) the biological availability to aquatic animals of radionuclides in Plowshare and other nuclear debris and the biological turnover of critical nuclides in specific aquatic animals; (6) the biological availability of Plowshare and other nuclear debris radionuclides to dairy cows and the transplacental transport of debris radionuclides in the dairy cow; (7) the persistence and behavior of radionuclides, particularly tritium, at sites of Plowshare and other nuclear detonations; and (8) somatic effects of Low Dose Radiation: Chromosome studies. (author)

Numerical simulation of the impact of water-air fronts on radionuclides plumes in heterogeneous media

International Nuclear Information System (INIS)

Aquino, J.; Francisco, A.S.; Pereira, F.; Amaral Souto, H.P.

2004-01-01

The goal of this paper is to investigate the interaction of water-air fronts with radionuclide plumes in unsaturated heterogeneous porous media. This problem is modeled by a system of equations that describes both the water-air flow and the radionuclide transport. The water-air problem is solved numerically by a mixed finite element combined with a non-oscillatory central difference scheme. For the radionuclide transport equation we use the Modified Method of Characteristics (MMOC). We present the results of numerical simulations for heterogeneous permeability fields taking into account sorption effects. (author)

Modelling of near-field radionuclide transport phenomena in a KBS-3V type of repository for nuclear waste with Goldsim Code - and verification against previous methods

International Nuclear Information System (INIS)

Pulkkanen, V.-M.; Nordman, H.

2010-03-01

Traditional radionuclide transport models overestimate significantly some phenomena, or completely ignore them. This motivates the development of new more precise models. As a result, this work is a description of commissioning of a new KBS-3V near-field radionuclide transport model, which has been done with a commercial software called GoldSim. According to earlier models, GoldSim model uses rz coordinates, but the solubilities of radionuclides have been treated more precisely. To begin with, the physical phenomena concerning near-field transport have been introduced according to GoldSim way of thinking. Also, the computational methods of GoldSim have been introduced and compared to methods used earlier. The actual verification of GoldSim model has been carried out by comparing the GoldSim results from simple cases to the corresponding results obtained with REPCOM, a software developed by VTT and used in several safety assessments. The results agree well. Finally, a few complicated cases were studied. In these cases, the REPCOM's limitations in handling of some phenomena become evident. The differences in the results are caused especially by the extension of the solubility limit to the whole computational domain, and the element-wise treatment of the solubilities which was used instead of nuclide-wise treatment. This work has been carried out as a special assignment to the former laboratory of Advanced Energy Systems in Helsinki University of Technology. The work was done at VTT. (orig.)

CIEMAT results in the frame of the european project Mechanisms governing the behaviour and transport of transuranics (analogues) and other radionuclides in marine ecosystems

International Nuclear Information System (INIS)

Gasco, C.; Anton, M.P.

1996-01-01

This report summarises the objectives and more relevant conclusions obtained by CIEMAT in the frame of the project Mechanisms governing the behaviour and transport of transuranics (analogues) and other radionuclides in marine ecosystems. The overall objective of this project was to identify the basic mechanisms and define the key parameters governing the physico-chemical speciation, vertical and horizontal mobility, biological magnification, incorporation to seabed sediments and ultimate fate of transuranium and other long-lived radionuclides in the marine environment, with a view to providing high-quality data of a universal character for use in the development and validation of predictive models based on fundamental mechanisms rather than the simpler box-model approach. This research was carried out in different European marine ecosystems: those directly affected by controlled releases from Nuclear Industries and/or accidents and those characterized by being preferent radionuclides accumulation sites (submarine canyons, estuaries, etc.). (Author)

Characterizing and modelling the radionuclide transport properties of fracture zones in plutonic rocks of the Canadian Shield

International Nuclear Information System (INIS)

Davison, C.C.; Kozak, E.T.; Frost, L.H.; Everitt, R.A.; Brown, A.; Gascoyne, M.; Scheier, N.W.

1999-01-01

Plutonic rocks of the Canadian Shield were investigated as a potential host medium for nuclear fuel waste disposal of used CANDU nuclear fuel. Field investigations at several geologic research areas on the Shield have shown that major fracture zones are the dominant pathways for the large scale movement of groundwater and solutes through plutonic rock bodies. Because of this, a significant amount of the geoscience work has focused on methods to identify, characterize and model the radionuclide transport properties of major fracture zones in the fractured plutonic rocks of the Shield. In order to quantify the transport properties of such fracture zones a series of, groundwater tracer tests were performed over a period of several years in several major, low dipping fracture zones. Sixteen tracer tests were performed using dipole recirculation methods to evaluate transport over distance scales ranging from 17 m to 700 m. It was concluded that only tracer tests can provide useful estimates of the effective porosity and dispersivity characteristics of these large fracture zones in plutonic rocks of the Canadian Shield. (author)

Environmental Baseline File National Transportation

International Nuclear Information System (INIS)

Harris, M.

1999-01-01

This Environmental Baseline File summarizes and consolidates information related to the national-level transportation of commercial spent nuclear fuel. Topics addressed include: shipments of commercial spent nuclear fuel based on mostly truck and mostly rail shipping scenarios; transportation routing for commercial spent nuclear fuel sites and DOE sites; radionuclide inventories for various shipping container capacities; transportation routing; populations along transportation routes; urbanized area population densities; the impacts of historical, reasonably foreseeable, and general transportation; state-level food transfer factors; Federal Guidance Report No. 11 and 12 radionuclide dose conversion factors; and national average atmospheric conditions

Comprehensive cooling water study annual report. Volume IV: radionuclide and heavy metal transport, Savannah River Plant

International Nuclear Information System (INIS)

Gladden, J.B.; Lower, M.W.; Mackey, H.E.; Specht, W.L.; Wilde, E.W.

1985-07-01

The principal sources of tritium, radiocesium, and radiocobalt in the environment at the Savannah River Plant have been reactor area effluent discharges to onsite streams. Radioactive releases began in 1955, with the period of major reactor releases occurring between 1955 and 1968. Since the early 1970s, releases, except for tritium releases, have been substantially reduced. Radioisotope liquid releases resulted specifically from leaching of reactor fuel elements with cladding failures which exposed the underlying fuel to water. The direct sources of these releases were heat exchanger cooling water, spent fuel storage and disassembly basin effluents, and process water from each of the reactor areas. Offsite radiochemical monitoring of water and sediment at upriver and downriver water treatment facilities indicates that SRP contributions of gamma-emitting radionuclide levels present at these facilities are minute. Tritium in water attributable to SRP operations is routinely detected at the downriver facilities; however, total alpha and nonvolatile beta concentrations attributable to SRP liquid releases are not detected at the downriver facilities. The historic material balance calculated for onsite releases of tritium transported to the Savannah River exhibits a high accounting of tritium released. Other radionuclides released to onsite streams have primarily remained in onsite floodplains. Radionuclide releases associated with reactor operations are derived primarily from disassembly basin water releases in the reactor areas and historically have been the major source of radioactivity released to onsite streams. The movement and interaction of these releases have been governed by cooling water discharges. Liquid releases continue to meet DOE concentration guides for the various radioisotopes in onsite streams and in the Savannah River

Transport of fallout and reactor radionuclides in the drainage basin of the Hudson River estuary

International Nuclear Information System (INIS)

Simpson, H.J.; Linsalata, P.; Olsen, C.R.; Cohen, N.; Trier, R.M.

1987-01-01

Fallout plutonium and radiocesium derived from both weapons testing and local reactor releases are found in the water column and sediments of the Hudson River in readily measurable amounts. The history of fallout delivery and dissolved phase runoff from the drainage basin of 80 Sr, 137 Cs, and /sup 239,240/Pu have been extensively documented since the mid-1950s. Sediment and water column concentrations of 134 Cs, 137 Cs, and /sup 239,240/Pu in the Hudson have also been documented since the mid-1960's and are summarized. Since the peak fallout years, substantial portions of the fallout radionuclides in the drainage basin have become unavailable to normal weathering processes as reflected by a measured decrease in the fallout nuclide transport to the waters of the tidal Hudson. Budget calculations indicate that plutonium may be transported into the estuary from the coastal ocean, and that desorption of radiocesium from particles has allowed a substantial fraction of radiocesium to be exported from the Hudson to marine waters. 29 references, 6 figures, 8 tables

Computer prediction of subsurface radionuclide transport: an adaptive numerical method

International Nuclear Information System (INIS)

Neuman, S.P.

1983-01-01

Radionuclide transport in the subsurface is often modeled with the aid of the advection-dispersion equation. A review of existing computer methods for the solution of this equation shows that there is need for improvement. To answer this need, a new adaptive numerical method is proposed based on an Eulerian-Lagrangian formulation. The method is based on a decomposition of the concentration field into two parts, one advective and one dispersive, in a rigorous manner that does not leave room for ambiguity. The advective component of steep concentration fronts is tracked forward with the aid of moving particles clustered around each front. Away from such fronts the advection problem is handled by an efficient modified method of characteristics called single-step reverse particle tracking. When a front dissipates with time, its forward tracking stops automatically and the corresponding cloud of particles is eliminated. The dispersion problem is solved by an unconventional Lagrangian finite element formulation on a fixed grid which involves only symmetric and diagonal matrices. Preliminary tests against analytical solutions of ne- and two-dimensional dispersion in a uniform steady state velocity field suggest that the proposed adaptive method can handle the entire range of Peclet numbers from 0 to infinity, with Courant numbers well in excess of 1

The flow of radionuclides through the Canadian archipelago

International Nuclear Information System (INIS)

Ellis, K.; Smith, J.N.

1999-01-01

The transport of contaminants to the Canadian Arctic by air and in water and their concentration through the marine food web has lead to enhanced levels of contaminants in several foods of Canadian northern inhabitants. Artificial radionuclides in the marine water can be used to determine water circulation and to trace contaminant transport through the Canadian Archipelago

A model for radionuclide transport by colloids in the geosphere

International Nuclear Information System (INIS)

Ledoux, E.

1993-01-01

This research project finds its place in the framework of the coordinated RADWAS-program and is found under the contract F12W-CT91-0079 of the Commission of European Communities. Five partners are involved in the project: Ecole des Mines de Paris/ARMINES (E. Ledoux, J. van der Lee); INTAKTA (M.D. de Cayeux); Rijksinstituut voor Volksgezondheid en Milieuhygiene (R. van der Weerd); CNRS-Laboratoire des Sciences du Genie Chimique (J. Dodds, M. Sardin, E. Rodier); ENRESA-CIEMAT (J. Astudillo, A. Hernandez). The main objective of the project is the development of a mathematical model for the migration of colloids and associated radionuclides in groundwaters through geological media. Laboratory migration experiments support the model development and will be used to test the validity of the computer codes. Furthermore, the model must be able to interpret field experiments in order to be applicable as a safety assessment tool for radioactive waste disposals. The project work can be divided into three parts: 1. Theoretical work including a literature survey, formulation of conceptual models, screening of phenomena by means of simple calculations and development of preliminary computer codes. Formulation of the general outline of a final mathematical concept. 2. Migration experiments in laboratory aimed at studying the fundamental transport mechanisms for colloidal substances. Model or artificial colloids are preferable in this stage to achieve fully controlled conditions. Modeling results will stimulate experimental design. Finally, natural geological media will be used to investigate the applicability of fundamental transport mechanisms to a more realistic environment. 3. Final model development, resulting in an operational tool for column experiments and long term safety assessment. A field data base will be compiled and applied to the model for validation purposes. 3 figs

Important processes affecting the release and migration of radionuclides from a deep geological repository

International Nuclear Information System (INIS)

Barátová, Dana; Nečas, Vladimír

2017-01-01

The processes that affect significantly the transport of contaminants through the near field and far field of a deep geological repository of spent nuclear fuel were studied. The processes can be generally divided into (i) processes related to the release of radionuclides from the spent nuclear fuel; (ii) processes related to the radionuclide transport mechanisms (such as advection and diffusion); and (iii) processes affecting the rate of radionuclide migration through the multi-barrier repository system. A near-field and geosphere model of an unspecified geological repository sited in a crystalline rock is also described. Focus of the treatment is on the effects of the different processes on the activity flow of the major safety-relevant radionuclides. The activity flow was simulated for one spent fuel cask by using the GoldSim simulation tool. (orig.)

SR 97 - Radionuclide transport calculations

Energy Technology Data Exchange (ETDEWEB)

Lindgren, Maria [Kemakta Konsult AB, Stockholm (Sweden); Lindstroem, Fredrik [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

1999-12-01

An essential component of a safety assessment is to calculate radionuclide release and dose consequences for different scenarios and cases. The SKB tools for such a quantitative assessment are used to calculate the maximum releases and doses for the hypothetical repository sites Aberg, Beberg and Ceberg for the initial canister defect scenario and also for the glacial melting case for Aberg. The reasonable cases, i.e. all parameters take reasonable values, results in maximum biosphere doses of 5x10{sup -8} Sv/yr for Aberg, 3x10{sup -8} Sv/yr for Beberg and 1x10{sup -8} Sv/yr for Ceberg for peat area. These doses lie significantly below 0.15 mSv/yr. (A dose of 0.15 mSv/yr for unit probability corresponds to the risk limit of 10{sup -5} per year for the most exposed individuals recommended in regulations.) The conclusion that the maximum risk would lie well below 10{sup -5} per year is also demonstrated by results from the probabilistic calculations, which directly assess the resulting risk by combining dose and probability estimates. The analyses indicate that the risk is 2x10{sup -5} Sv/yr for Aberg, 8x10{sup -7} Sv/yr for Beberg and 3x10{sup -8} Sv/yr for Ceberg. The analysis shows that the most important parameters in the near field are the number of defective canisters and the instant release fraction. The influence from varying one parameter never changes the doses as much as an order of magnitude. In the far field the most important uncertainties affecting release and retention are associated with permeability and connectivity of the fractures in the rock. These properties affect several parameters. Highly permeable and well connected fractures imply high groundwater fluxes and short groundwater travel times. Sparsely connected or highly variable fracture properties implies low flow wetted surface along migration paths. It should, however, be remembered that the far-field parameters have little importance if the near-field parameters take their reasonable

SR 97 - Radionuclide transport calculations

International Nuclear Information System (INIS)

Lindgren, Maria; Lindstroem, Fredrik

1999-12-01

An essential component of a safety assessment is to calculate radionuclide release and dose consequences for different scenarios and cases. The SKB tools for such a quantitative assessment are used to calculate the maximum releases and doses for the hypothetical repository sites Aberg, Beberg and Ceberg for the initial canister defect scenario and also for the glacial melting case for Aberg. The reasonable cases, i.e. all parameters take reasonable values, results in maximum biosphere doses of 5x10 -8 Sv/yr for Aberg, 3x10 -8 Sv/yr for Beberg and 1x10 -8 Sv/yr for Ceberg for peat area. These doses lie significantly below 0.15 mSv/yr. (A dose of 0.15 mSv/yr for unit probability corresponds to the risk limit of 10 -5 per year for the most exposed individuals recommended in regulations.) The conclusion that the maximum risk would lie well below 10 -5 per year is also demonstrated by results from the probabilistic calculations, which directly assess the resulting risk by combining dose and probability estimates. The analyses indicate that the risk is 2x10 -5 Sv/yr for Aberg, 8x10 -7 Sv/yr for Beberg and 3x10 -8 Sv/yr for Ceberg. The analysis shows that the most important parameters in the near field are the number of defective canisters and the instant release fraction. The influence from varying one parameter never changes the doses as much as an order of magnitude. In the far field the most important uncertainties affecting release and retention are associated with permeability and connectivity of the fractures in the rock. These properties affect several parameters. Highly permeable and well connected fractures imply high groundwater fluxes and short groundwater travel times. Sparsely connected or highly variable fracture properties implies low flow wetted surface along migration paths. It should, however, be remembered that the far-field parameters have little importance if the near-field parameters take their reasonable values. In that case almost all

Radionuclide transport calculations from high-level long-lived radioactive waste disposal in deep clayey geologic formation toward adjacent aquifers

International Nuclear Information System (INIS)

Genty, A.; Le Potier, C.

2007-01-01

In the context of high-level nuclear waste repository safety calculations, the modeling of radionuclide migration is of first importance. Three dimensional radionuclide transport calculations in geological repository need to describe objects of the meter scale embedded in geologic layer formations of kilometer extension. A complete and refined spatial description would end up with at least meshes of hundreds of millions to billions elements. The resolution of this kind of problem is today not reachable with classical computers due to resources limitations. Although parallelized computation appears as potential tool to handle multi-scale calculations, to our knowledge no attempt have been yet performed. One emerging solution for repository safety calculations on very large cells meshes consists in using a domain decomposition approach linked to massive parallelized computer calculation. In this approach, the repository domain is divided in small elementary domains and transport calculation are performed independently on different processor for each elementary domain. Before to develop this possible solution, we performed some preliminary test in order to access the order of magnitude of cells needed to perform converged calculation on one elementary disposal domain and to check if Finite Volume (FV) based on Multi Point Flux Approximation (MPFA) spatial scheme or more classical Mixed Hybrid Finite Element (MHFE) spatial scheme were adapted for those calculations in highly heterogeneous porous media. Our preliminary results point out that MHFE and VF schemes applied on non-parallelepiped hexahedral cells for flow and transport calculations in highly heterogeneous media gave satisfactory results. Nevertheless further investigations and additional calculations are needed in order to exhibit the mesh discretization level needed to perform converged calculations. (authors)

The release of organic material from clay based buffer materials and its potential implications for radionuclide transport

International Nuclear Information System (INIS)

Vilks, P.; Stroes-Gascoyne, S.; Goulard, M.; Haveman, S.A.; Bachinski, D.B.

1998-01-01

In the Canadian nuclear fuel waste disposal concept used fuel would be placed in corrosion resistant containers which would be surrounded by clay-based buffer and backfill materials in an engineered vault excavated at 500 to 1000 m depth in crystalline rock formations in the Canadian shield. Organic substances could affect radionuclide mobility due to the effects of redox and complexation reactions that increase solubility and alter mobility. The purpose of this study was to determine whether the buffer and backfill materials, proposed for use in a disposal vault, contain organics that could be leached by groundwater in large enough quantities to affect radionuclide mobility within the disposal vault and surrounding geosphere complex. Buffer material, made from a mixture of 50 wt.% Avonlea sodium bentonite and 50 wt.% silica sand, was extracted with deionized water to determine the release of dissolved organic carbon (DOC), humic acid and fulvic acid. The effect of radiation and heat from the used fuel was simulated by treating samples of buffer before leaching to various amounts of heat (60 and 90 C) for periods of 2, 4 and 6 weeks, and to ionizing radiation with doses of 25 kGy and 50 kGy. The results showed that groundwater would leach significant amounts of organics from buffer that complex with radionuclides such as the actinides, potentially affecting their solubility and transport within the disposal vault and possibly the surrounding geosphere. In addition, the leached organics would likely stimulate microbial growth by several orders of magnitude. Heating and radiation affect the amount and nature of leachable organics. (orig.)

Effects of sorption hysteresis on radionuclide releases from waste packages

International Nuclear Information System (INIS)

Barney, G.S.; Reed, D.T.

1985-01-01

A one-dimensional, numerical transport model was used to calculate radionuclide releases from waste packages emplaced in a nuclear waste repository in basalt. The model incorporates both sorption and desorption isotherm parameters measured previously for sorption of key radionuclides on the packing material component of the waste package. Sorption hysteresis as described by these isotherms lowered releases of some radionuclides by as much as two orders of magnitude. Radionuclides that have low molar inventories (relative to uranium), high solubility, and strongly sorbed, are most affected by sorption hysteresis. In these cases, almost the entire radionuclide inventory is sorbed on the packing material. The model can be used to help optimize the thickness of the packing material layer by comparing release rate versus packing material thickness curves with Nuclear Regulatory Commission (NRC) and Environmental Protection Agency (EPA) release limits

Database for radionuclide transport in the biosphere: nuclide specific and geographic data for northern Switzerland

International Nuclear Information System (INIS)

Jiskra, J.

1985-01-01

The biosphere model is the final link in the chain of radionuclide transport models, used for radiation dose calculations from high-level waste repositories. This report presents the data needed for biosphere calculations and discusses them where necessary. The first part is dedicated to the nuclide specific parameters like distribution coefficients (water -soil), concentration ratios (soil - plant) and distribution factors (for milk, meat, etc.) which are reported in the literature. The second part contains the choice of regions, their division into compartments and the discussion of nutritional habits for man and animals. At the end a theoretical human population for each region is estimated based on the consumption rates and on the yield of agricultural products, assuming an autonomous nutrition. (author)

Modelling of the radionuclide transport through terrestrial food chains

International Nuclear Information System (INIS)

Hanusik, V.

1991-01-01

The paper presents a terrestrial food chains model for computing potential human intake of radionuclides released into the atmosphere during normal NPP operation. Attention is paid to the choice of model parameter values. Results obtained by our approach are compared to those applied in current methodology. (orig.) [de

Statistical analysis of fallout radionuclides transfer to paddy-field rice

International Nuclear Information System (INIS)

Takahashi, T.; Morisawa, S.; Inoue, Y.

1996-01-01

Radionuclides released from nuclear facilities to atmosphere are transported through various pathways in biosphere and cause human exposure. Among these radionuclides transfer pathways, an ingestion of crops containing radionuclides is one of the dominant pathway for human exposure. For the safety assessment of nuclear facilities, it is important to understand the behavior of radionuclides in agricultural environment and to describe them in a mathematical model. In this paper, a statistical model is proposed for estimating the concentration of fallout radionuclides in paddy-field rice, the staple food for Japanese people. For describing behavior of fallout radionuclides in a paddy-field, a dynamic model and a statistical model have been proposed respectively. The model used in this study has been developed assuming that the amount of radionuclides transfer to brown rice (hulled rice) or polished rice through direct deposition of airborne radionuclides (the direct deposition pathway) and root uptake from a paddy soil (the root uptake pathway) are proportional to the deposition flux of radionuclides and concentration of radionuclides in paddy soil respectively. That is, the model has two independent variables; the deposition flux of radionuclides and the concentration of radionuclides in the paddy soil, and has single dependent variable; the concentration of radionuclides in brown rice or polished rice. The regression analysis is applied by using environmental monitoring data. Then the distribution of radionuclides between rice-bran (skin part of rice crop) and polished rice (core part) through both the direct deposition pathway and the root uptake pathway are evaluated by the model. (author)

Formation and transport of radioactive colloids in porous media

International Nuclear Information System (INIS)

Chung, J.Y.; Lee, K.J.

1993-01-01

This paper deals with the effect of the presence of colloids in natural groundwater on radionuclide transport. The system considered here treats groundwater as a dispersing medium and colloid or finely divided solid material resulting from several different repository sources as a dispersed phase. Evaluation of the radionuclides adsorption on colloid, concepts of effective transport velocity and migration distance, and mathematical formulation of the filtration equation were driven, along with the case studies using typical parameter values of a conceptual radioactive waste repository and concentration on the effect of poly dispersed colloid on radionuclide transport. This paper also introduces the three phase analysis to treat the radionuclide transport more practically. When compared with the previously published experimental data, the modified filtration equation gives a satisfactory result. Results of the case studies show that the reduction of colloidal size enhances the corresponding colloid concentration when colloidal transport is only affected by diffusion phenomena. However, the three phase analysis shows that this trend can be reversed if the colloidal filtration becomes a dominant mechanism in the colloidal transport. Consequently, these results show that colloid could play a very important role in radionuclide transport under a repository environment

Sensitivity analysis on retardation effect of natural barriers against radionuclide transport

International Nuclear Information System (INIS)

Hatanaka, K.

1994-01-01

The generic performance assessment of the geological disposal system for high level waste (HLW) in Japan has been carried out by the Power Reactor and Nuclear Fuel Development Corporation (PNC) in accordance with the overall HLW management program defined by the Atomic Energy Commission of Japan. The Japanese concept of the geological disposal system is based on a multi-barrier system which is composed of vitrified waste, carbon steel overpack, thick bentonite buffer and a variety of realistic geological conditions. The main objectives of the study are the detailed analysis of the performance of engineered barrier system (EBS) and the analysis of the performance of natural barrier system (NBS) and the evaluation of its compliance with the required overall system performance. Sensitivity analysis was carried out for the objectives to investigate the way and extent of the retardation in the release to biosphere by the effect of NBS, and to clarify the conditions which is sufficient to ensure that the overall system meets safety requirement. The radionuclide transport model in geological media, the sensitivity analysis, and the calculated results of the retardation effect of NBS in terms of the sensitivity parameters are reported. (K.I.)

Modeling Groundwater Flow and Transport of Radionuclides at Amchitka Island's Underground Nuclear Tests: Milrow, Long Shot, and Cannikin

Energy Technology Data Exchange (ETDEWEB)

Ahmed Hassan; Karl Pohlmann; Jenny Chapman

2002-11-19

Since 1963, all United States nuclear tests have been conducted underground. A consequence of this testing has been the deposition of large amounts of radioactive material in the subsurface, sometimes in direct contact with groundwater. The majority of this testing occurred on the Nevada Test Site (NTS), but a limited number of experiments were conducted in other locations. One of these locations, Amchitka Island, Alaska is the subject of this report. Three underground nuclear tests were conducted on Amchitka Island. Long Shot was an 80-kiloton-yield test conducted at a depth of 700 meters (m) on October 29, 1965 (DOE, 2000). Milrow had an announced yield of about 1,000 kilotons, and was detonated at a depth of 1,220 m on October 2, 1969. Cannikin had an announced yield less than 5,000 kilotons, and was conducted at a depth of 1,790 m on November 6, 1971. The purpose of this work is to provide a portion of the information needed to conduct a human-health risk assessment of the potential hazard posed by the three underground nuclear tests on Amchitka Island. Specifically, the focus of this work is the subsurface transport portion, including the release of radionuclides from the underground cavities and their movement through the groundwater system to the point where they seep out of the ocean floor and into the marine environment. This requires a conceptual model of groundwater flow on the island using geologic, hydrologic, and chemical information, a numerical model for groundwater flow, a conceptual model of contaminant release and transport properties from the nuclear test cavities, and a numerical model for contaminant transport. Needed for the risk assessment are estimates of the quantity of radionuclides (in terms of mass flux) from the underground tests on Amchitka that could discharge to the ocean, the time of possible discharge, and the location in terms of distance from shoreline. The radionuclide data presented here are all reported in terms of normalized

Bio-inspired digital signal processing for fast radionuclide mixture identification

Science.gov (United States)

Thevenin, M.; Bichler, O.; Thiam, C.; Bobin, C.; Lourenço, V.

2015-05-01

Countries are trying to equip their public transportation infrastructure with fixed radiation portals and detectors to detect radiological threat. Current works usually focus on neutron detection, which could be useless in the case of dirty bomb that would not use fissile material. Another approach, such as gamma dose rate variation monitoring is a good indication of the presence of radionuclide. However, some legitimate products emit large quantities of natural gamma rays; environment also emits gamma rays naturally. They can lead to false detections. Moreover, such radio-activity could be used to hide a threat such as material to make a dirty bomb. Consequently, radionuclide identification is a requirement and is traditionally performed by gamma spectrometry using unique spectral signature of each radionuclide. These approaches require high-resolution detectors, sufficient integration time to get enough statistics and large computing capacities for data analysis. High-resolution detectors are fragile and costly, making them bad candidates for large scale homeland security applications. Plastic scintillator and NaI detectors fit with such applications but their resolution makes identification difficult, especially radionuclides mixes. This paper proposes an original signal processing strategy based on artificial spiking neural networks to enable fast radionuclide identification at low count rate and for mixture. It presents results obtained for different challenging mixtures of radionuclides using a NaI scintillator. Results show that a correct identification is performed with less than hundred counts and no false identification is reported, enabling quick identification of a moving threat in a public transportation. Further work will focus on using plastic scintillators.

MARFA version 3.2.2 user's manual: migration analysis of radionuclides in the far field

International Nuclear Information System (INIS)

Painter, Scott; Mancillas, James

2009-12-01

The computer code Migration Analysis of Radionuclides in the Far Field (MARFA) uses a particle-based Monte Carlo method to simulate the transport of radionuclides in a sparsely fractured geological medium. Transport in sparsely fractured rock is of interest because this medium may serve as a barrier to migration of radionuclides to the accessible environment. The physical processes represented in MARFA include advection, longitudinal dispersion, Fickian diffusion into an infinite or finite rock matrix, equilibrium sorption, decay, and in-growth. Multiple non-branching decay chains of arbitrary length are supported. This document describes the technical basis and input requirements for MARFA Version 3.2.2. MARFA Version 3.2 included new capabilities to accommodate transient flow velocities and sorption parameters, which are assumed to be piecewise constant in time. Version 3.2.1 was a minor change from Version 3.2 to allow a more convenient input format for sorption information. New capabilities in Version 3.2.2 include an option to specify a non-zero start time for the simulation, an optional input parameter that decreases the amount of retention within a single fracture because of flow channeling, and an alternative method for sampling the radionuclide source. MARFA uses the particle on random streamline segment algorithm /Painter et al. 2006/, a Monte Carlo algorithm combining time-domain random walk methods with pathway stochastic simulation. The algorithm uses non-interacting particles to represent packets of radionuclide mass. These particles are moved through the system according to rules that mimic the underlying physical transport and retention processes. The set of times required for particles to pass through the geological barrier are then used to reconstruct discharge rates (mass or activity basis). Because the algorithm uses non-interacting particles, the transport and retention processes are limited to those that depend linearly on radionuclide

Complementary modelling of radionuclide retention in the near-surface system at Forsmark. Development of a reactive transport model using Forsmark 1.2 data

Energy Technology Data Exchange (ETDEWEB)

Sena, Clara; Grandia, Fidel; Arcos, David; Molinero, Jorge; Duro, Lara (Amphos XXI Consulting S.L., Barcelona (Spain))

2008-10-15

sensitivity analysis of the more relevant parameters considered in the reactive transport numerical models is also presented here. From the main report of the SR-Can project it is stated that Ra is one of the radionuclides with greater contribution to the radioactive doses that might be transferred to the biosphere in the context of repository release. For this reason, Ra was added to the set of radionuclides (Sr, Cs, and U). Another improvement in the numerical simulations presented here is the calculation of the hydrogeochemical steady state of the near-surface system, prior to repository release. This is done to approach the present-day conditions at Forsmark. In addition, radionuclides derived from repository release have been discriminated from those of natural origin, already present in the groundwaters. Radionuclides coming from repository were labelled as RDCs, RDSr, and RDU (RD stands for repository-derived). Ra was not labelled since the presence of this radionuclide in the modelled domain is exclusively attributed to repository release due to the extremely low concentrations observed in the natural waters of Forsmark. The results attained in the reactive transport models built in this work show that the near-surface systems at Forsmark constitute a geochemical reactive barrier able to retain radionuclides by several key processes, namely cation exchange, adsorption on mineral surfaces and precipitation of pure phases and solid solutions. The reactive transport simulations predict that repository-derived Sr, U, and Cs are retained in the solid phase of both Quaternary deposits under study, while Ra is effectively retained in the till deposit only. Ra is not retained in the glacial clay deposit since saturation of barite, which is the only retention mechanism considered in the simulations for this radionuclide, is not reached in this system. The simulations indicate that, in the till deposit, Sr is retained via cation exchange and coprecipitation with calcite, U is

Environmental Baseline File for National Transportation

International Nuclear Information System (INIS)

1999-01-01

This Environmental Baseline File summarizes and consolidates information related to the national-level transportation of commercial spent nuclear fuel. Topics address include: shipments of commercial spent nuclear fuel based on mostly truck and mostly rail shipping scenarios; transportation routing for commercial spent nuclear fuel sites and DOE sites; radionuclide inventories for various shipping container capacities; transportation routing; populations along transportation routes; urbanized area population densities; the impacts of historical, reasonably foreseeable, and general transportation; state-level food transfer factors; Federal Guidance Report No. 11 and 12 radionuclide dose conversion factors; and national average atmospheric conditions

Microbiological Transformations of Radionuclides in the Subsurface

International Nuclear Information System (INIS)

Marshall, Matthew J.; Beliaev, Alex S.; Fredrickson, Jim K.

2010-01-01

Microorganisms are ubiquitous in subsurface environments although their populations sizes and metabolic activities can vary considerably depending on energy and nutrient inputs. As a result of their metabolic activities and the chemical properties of their cell surfaces and the exopolymers they produce, microorganisms can directly or indirectly facilitate the biotransformation of radionuclides, thus altering their solubility and overall fate and transport in the environment. Although biosorption to cell surfaces and exopolymers can be an important factor modifying the solubility of some radionuclides under specific conditions, oxidation state is often considered the single most important factor controlling their speciation and, therefore, environmental behavior.

Illicit Trafficking of Natural Radionuclides

Science.gov (United States)

Friedrich, Steinhäusler; Lyudmila, Zaitseva

2008-08-01

Natural radionuclides have been subject to trafficking worldwide, involving natural uranium ore (U 238), processed uranium (yellow cake), low enriched uranium (20% U 235), radium (Ra 226), polonium (Po 210), and natural thorium ore (Th 232). An important prerequisite to successful illicit trafficking activities is access to a suitable logistical infrastructure enabling an undercover shipment of radioactive materials and, in case of trafficking natural uranium or thorium ore, capable of transporting large volumes of material. Covert en route diversion of an authorised uranium transport, together with covert diversion of uranium concentrate from an operating or closed uranium mines or mills, are subject of case studies. Such cases, involving Israel, Iran, Pakistan and Libya, have been analyzed in terms of international actors involved and methods deployed. Using international incident data contained in the Database on Nuclear Smuggling, Theft and Orphan Radiation Sources (DSTO) and international experience gained from the fight against drug trafficking, a generic Trafficking Pathway Model (TPM) is developed for trafficking of natural radionuclides. The TPM covers the complete trafficking cycle, ranging from material diversion, covert material transport, material concealment, and all associated operational procedures. The model subdivides the trafficking cycle into five phases: (1) Material diversion by insider(s) or initiation by outsider(s); (2) Covert transport; (3) Material brokerage; (4) Material sale; (5) Material delivery. An Action Plan is recommended, addressing the strengthening of the national infrastructure for material protection and accounting, development of higher standards of good governance, and needs for improving the control system deployed by customs, border guards and security forces.

Illicit Trafficking of Natural Radionuclides

International Nuclear Information System (INIS)

Friedrich, Steinhaeusler; Lyudmila, Zaitseva

2008-01-01

Natural radionuclides have been subject to trafficking worldwide, involving natural uranium ore (U 238), processed uranium (yellow cake), low enriched uranium ( 20% U 235), radium (Ra 226), polonium (Po 210), and natural thorium ore (Th 232). An important prerequisite to successful illicit trafficking activities is access to a suitable logistical infrastructure enabling an undercover shipment of radioactive materials and, in case of trafficking natural uranium or thorium ore, capable of transporting large volumes of material. Covert en route diversion of an authorised uranium transport, together with covert diversion of uranium concentrate from an operating or closed uranium mines or mills, are subject of case studies. Such cases, involving Israel, Iran, Pakistan and Libya, have been analyzed in terms of international actors involved and methods deployed. Using international incident data contained in the Database on Nuclear Smuggling, Theft and Orphan Radiation Sources (DSTO) and international experience gained from the fight against drug trafficking, a generic Trafficking Pathway Model (TPM) is developed for trafficking of natural radionuclides. The TPM covers the complete trafficking cycle, ranging from material diversion, covert material transport, material concealment, and all associated operational procedures. The model subdivides the trafficking cycle into five phases: (1) Material diversion by insider(s) or initiation by outsider(s); (2) Covert transport; (3) Material brokerage; (4) Material sale; (5) Material delivery. An Action Plan is recommended, addressing the strengthening of the national infrastructure for material protection and accounting, development of higher standards of good governance, and needs for improving the control system deployed by customs, border guards and security forces

Sediment transport modelling in the Gulf of Lion with the perspective of studying the fate of radionuclides originated by the Rhone River

International Nuclear Information System (INIS)

Dufois, Francois

2008-01-01

Among the various contaminants introduced in the environment, artificial radionuclides appear particularly important to consider because of their chemical toxicity and / or of their radio-toxicity. Some radionuclides present a high affinity with particles so that the study of the sediment dynamics is a useful preliminary to the study of their dispersion on the open sea. This thesis is focused on the fate of sediments in the Gulf of Lion (NW Mediterranean sea) and in particular on the impact of the Rhone River, which is the main source of particulate matter in the Gulf of Lion. In order to study the sediment transport mechanisms on various space and time scales, this thesis is based on mathematical modelling. The hydro-sedimentary model set up in the Gulf of Lion, which takes into account the gathered effect of waves and currents, was supported by recent hydro-sedimentary data analyses. CARMA (winter 2006/2007) and SCOPE (winter 2007/2008) experiments were used to better understand the physical processes which control the sediment transport on the Rhone pro-delta and to validate the model. The period of the centennial Rhone River flood of December 2003 was also simulated in order to determine the impact of such extreme events on the fate of sediments. Both observations and simulations of the studied periods highlight the high capacity of erosion and transport induced by south-eastern storms on the pro-delta

An Updated Site Scale Saturated Zone Ground Water Transport Model For Yucca Mountain

International Nuclear Information System (INIS)

S. Kelkar; H. Viswanathan; A. Eddebbarrh; M. Ding; P. Reimus; B. Robinson; B. Arnold; A. Meijer

2006-01-01

The Yucca Mountain site scale saturated zone transport model has been revised to incorporate the updated flow model based on a hydrogeologic framework model using the latest lithology data, increased grid resolution that better resolves the geology within the model domain, updated Kd distributions for radionuclides of interest, and updated retardation factor distributions for colloid filtration. The resulting numerical transport model is used for performance assessment predictions of radionuclide transport and to guide future data collection and modeling activities. The transport model results are validated by comparing the model transport pathways with those derived from geochemical data, and by comparing the transit times from the repository footprint to the compliance boundary at the accessible environment with those derived from 14 C-based age estimates. The transport model includes the processes of advection, dispersion, fracture flow, matrix diffusion, sorption, and colloid-facilitated transport. The transport of sorbing radionuclides in the aqueous phase is modeled as a linear, equilibrium process using the Kd model. The colloid-facilitated transport of radionuclides is modeled using two approaches: the colloids with irreversibly embedded radionuclides undergo reversible filtration only, while the migration of radionuclides that reversibly sorb to colloids is modeled with modified values for sorption coefficient and matrix diffusion coefficients. Model breakthrough curves for various radionuclides at the compliance boundary are presented along with their sensitivity to various parameters

Compilation of data for radionuclide transport analysis

International Nuclear Information System (INIS)

2001-11-01

This report is one of the supporting documents to the updated safety assessment (project SAFE) of the Swedish repository for low and intermediate level waste, SFR 1. A number of calculation cases for quantitative analysis of radionuclide release and dose to man are defined based on the expected evolution of the repository, geosphere and biosphere in the Base Scenario and other scenarios selected. The data required by the selected near field, geosphere and biosphere models are given and the values selected for the calculations are compiled in tables. The main sources for the selected values of the migration parameters in the repository and geosphere models are the safety assessment of a deep repository for spent fuel, SR 97, and the preliminary safety assessment of a repository for long-lived, low- and intermediate level waste, SFL 3-5. For the biosphere models, both site-specific data and generic values of the parameters are selected. The applicability of the selected parameter values is discussed and the uncertainty is qualitatively addressed for data to the repository and geosphere migration models. Parameter values selected for these models are in general pessimistic in order not to underestimate the radionuclide release rates. It is judged that this approach combined with the selected calculation cases will illustrate the effects of uncertainties in processes and events that affects the evolution of the system as well as in quantitative data that describes this. The biosphere model allows for probabilistic calculations and the uncertainty in input data are quantified by giving minimum, maximum and mean values as well as the type of probability distribution function

Compilation of data for radionuclide transport analysis

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-11-01

This report is one of the supporting documents to the updated safety assessment (project SAFE) of the Swedish repository for low and intermediate level waste, SFR 1. A number of calculation cases for quantitative analysis of radionuclide release and dose to man are defined based on the expected evolution of the repository, geosphere and biosphere in the Base Scenario and other scenarios selected. The data required by the selected near field, geosphere and biosphere models are given and the values selected for the calculations are compiled in tables. The main sources for the selected values of the migration parameters in the repository and geosphere models are the safety assessment of a deep repository for spent fuel, SR 97, and the preliminary safety assessment of a repository for long-lived, low- and intermediate level waste, SFL 3-5. For the biosphere models, both site-specific data and generic values of the parameters are selected. The applicability of the selected parameter values is discussed and the uncertainty is qualitatively addressed for data to the repository and geosphere migration models. Parameter values selected for these models are in general pessimistic in order not to underestimate the radionuclide release rates. It is judged that this approach combined with the selected calculation cases will illustrate the effects of uncertainties in processes and events that affects the evolution of the system as well as in quantitative data that describes this. The biosphere model allows for probabilistic calculations and the uncertainty in input data are quantified by giving minimum, maximum and mean values as well as the type of probability distribution function.

The behavior of radionuclides in the soils of Rocky Flats, Colorado

Energy Technology Data Exchange (ETDEWEB)

Litaor, M I [Tel-Hai Rodman Coll., Upper Galilee (Israel); Barth, G; Zika, E M; Litus, G; Moffitt, J; Daniels, H [Colorado Univ., Civil and Environmental Engineering Dept., Boulder, CO (United States)

1998-05-01

Radionuclide contamination of soils in Rocky Flats, Colorado, resulted from leaking drums of Pu-contaminated oil stored at an outdoor area. To evaluated the mechanisms of radionuclide transport from the contaminated soils to groundwater, an advanced monitoring system was installed across a toposequence. The impact of natural rain, snowmelt, and large-scale rain simulations on the mobility and distribution of the radionuclides in soil interstitial water was studied. The distribution of radionuclides during the monitoring period from 1993 to 1995 suggested that Pu-239 + 240 and Am-241 are largely immobile in semi-arid soils. Fractionation of Pu-239 + 240 and Am-241 to different particle sizes in the soil interstitial water suggested that most of the radionuclides (83-97%) were associated with suspended particles, whereas the level of radionuclides associated with colloidal (0.45 {mu}m > X > 1 nm) and nonfilterable (< 1 nm) fractions ranged from 1.5 to 15%. (author).

Preliminary report on retardation factors and radionuclide migration

International Nuclear Information System (INIS)

Isherwood, D.

1977-01-01

Available data on distribution coefficients for the biologically important radionuclides present in high-level waste were used to estimate retardation factors (K/sub f/) for a mass transport hydrologic model. The radionuclides were divided into 3 groups: fission products with no sorption (K/sub f/ = 1), fission products with sorption (K/sub f/ = 10 2 ), and the actinides and their daughter products (K/sub f/ = 10 4 ). Minimum and maximum values were assigned the latter two groups. Uncertainties as a function of time were estimated at +- an order of magnitude. 39 references, 5 tables

Identification of key radionuclides in a nuclear waste repository in basalt

International Nuclear Information System (INIS)

Barney, G.S.; Wood, B.J.

1980-05-01

Radionuclides were identified which appear to pose the greatest potential hazard to man during long-term storage of nuclear waste in a repository mined in the Columbia Plateau basalt formation. The criteria used to select key radionuclides were as follows: quantity of radionuclide in stored waste; biological toxicity; leach rate of the wastes into groundwater; and transport rate via groundwater flow. The waste forms were assumed to be either unreprocessed spent fuel or borosilicate glass containing reprocessed high-level waste. The nuclear waste composition was assumed to be that from a light water reactor. Radionuclides were ranked according to quantity, toxicity, and release rate from the repository. These rankings were combined to obtain a single list of key radionuclides. The ten most important radionuclides in order of decreasing hazard are: 99 Tc, 129 I, 237 Np, 226 Ra, 107 Pd, 230 Th, 210 Pb, 126 Sn, 79 Se, and 242 Pu. Safety assessment studies and the design of engineered barriers should concentrate on containment of radionuclides in this list

Resuspension and redistribution of radionuclides during grassland and forest fires in the Chernobyl exclusion zone: part II. Modeling the transport process

International Nuclear Information System (INIS)

Yoschenko, V.I.; Kashparov, V.A.; Levchuk, S.E.; Glukhovskiy, A.S.; Khomutinin, Yu.V.; Protsak, V.P.; Lundin, S.M.; Tschiersch, J.

2006-01-01

To predict parameters of radionuclide resuspension, transport and deposition during forest and grassland fires, several model modules were developed and adapted. Experimental data of controlled burning of prepared experimental plots in the Chernobyl exclusion zone have been used to evaluate the prognostic power of the models. The predicted trajectories and elevations of the plume match with those visually observed during the fire experiments in the grassland and forest sites. Experimentally determined parameters could be successfully used for the calculation of the initial plume parameters which provide the tools for the description of various fire scenarios and enable prognostic calculations. In summary, the model predicts a release of some per mille from the radionuclide inventory of the fuel material by the grassland fires. During the forest fire, up to 4% of 137 Cs and 9 Sr and up to 1% of the Pu isotopes can be released from the forest litter according to the model calculations. However, these results depend on the parameters of the fire events. In general, the modeling results are in good accordance with the experimental data. Therefore, the considered models were successfully validated and can be recommended for the assessment of the resuspension and redistribution of radionuclides during grassland and forest fires in contaminated territories

Release and transport of artificial radionuclides from nuclear weapons related activities in the Ob River, Siberia over the course of the nuclear age

International Nuclear Information System (INIS)

Sayles, F.L.; Kenna, T.C.; Livingston, H.D.

1999-01-01

Studies of sediment cores from lakes on the flood plain of the Ob River, Siberia have been used to develop a history of the release, transport, and deposition of artificial radionuclides related to the development and testing of nuclear weapons over the duration of the nuclear age (∼1950 to the present) in this major Arctic river system. The Ob is of particular importance in this regard as two of the former Soviet Union's major weapons production plants, Mayak and Tomsk-7, and the Semipalatinsk test site are located within the Ob drainage basin. Accidents and intentional releases of radionuclides at both plants have been substantial, raising the issue of transport throughout this extensive river system as well as delivery to the Arctic Ocean. Our studies have included determining sediment profiles of 239,240 Pu, 137 Cs, and the natural nuclide 210 Pb and its parent 226 Ra in a number of cores from the Ob delta, as well as analysis of 239 Pu, 240 Pu, and 237 Np. The latter provide sensitive measures of the presence of non-fallout materials derived from weapons production activities

Inclusion of radionuclides absorption by sediments in the RIVLAK program

International Nuclear Information System (INIS)

Rodrigues Junior, O.; Moreira, J.M.L.

1992-01-01

The RIVLAK code solves the one-dimensional transport equation for radionuclide concentrations within a water body for routine and accidental releases of liquid effluents. The principal phenomena considered in the RIVLAK code are advection by the water body flow, longitudinal and transversal diffusion, and radioactive decay. This work incorporates the interaction between radionuclides and suspended or bed sediments to the RIVLAK code. An approximate equation for the radionuclide concentration in an effective sediment is included in the code with explicit terms for adsorption and desorption from the water to the effective sediment. The modified RIVLAK code is utilized for estimating the radionuclide concentration from release experiments in the Clinch river. The original code overestimates the Cs concentration downstream by approximately two orders of magnitude. The modified version predicts the Cs concentration with few percents, and underestimates its longitudinal dispersion by about 35%. The special care needed with parameters such as the radionuclide diffusion coefficient in the water, and the adsorption and desorption coefficients are discussed. (author)

ROOTS: a program to generate radionuclide decay chains

International Nuclear Information System (INIS)

Fields, D.E.; Dunning, D.E. Jr.

1985-11-01

A set of algorithms has been developed to support dosimetric and transport calculations. These subroutines read a radionuclide data file and prepare a decay chain showing branching fractions and radioactive half-lives of each member. One application of these subroutines has been their implementation as a set of FORTRAN subroutines for application in the PREREM code (Ryan and Fields, 1981). Recent use of these subroutines in stand-alone form required their expansion to print branching fractions. An expanded data set based on ICRP-38 radionuclide data (ICRP, 1983) was also prepared. This subroutine package is called Radionuclide Origin and Ontogeny Tracing Subroutines (ROOTS). The package is intended for execution on a Digital Equipment Corporation PDP-10 Computer System, and may require modification to run on other machines. 6 refs

On the optimization of empirical data concerning radionuclides in water of Lake Juodis

International Nuclear Information System (INIS)

Tarasiuk, N.; Koviazina, E.; Shliahtich, E.

2004-01-01

Quality of site-dependent water sampling for radionuclide analysis assessing their removal from the complicated aquatic system of eutrophic Lake Juodis is analyzed comparing time courses of site-specific data on standard variables (pH, temperature, redox potential, oxygen concentration, conductivity) in 2003-2004. Compared data were measured simultaneously: a) in the open bottom terrace of the lake adjoining its outflow; b) before the beaver dam bounding the lake rush grown area and c) at the site of the outflowing brook usually used for water sampling for radionuclide analysis. The rush grown area adjoining the outflowing brook is a natural filter for plutonium transport from the lake during warm season as well as for radiocesium activity fraction associated with the suspended matter. Using information on site-specific variations of vertical profiles of standard variables measured in the shallow bottom terrace of the lake, seasonal peculiarities of vertical radionuclide transport in the water column and their release from the sediments are discussed. In winter beaver activities in the lake as well as formation of the anaerobic zone in the rush grown area are considered as supplementary mechanisms facilitating vertical transport of radionuclides in the temperature stratificated water column and their removal from similar lakes. (author)

Recommendations concerning classification of and discharge standards for radionuclide laboratories

International Nuclear Information System (INIS)

1985-01-01

In the report recommendations are made for the limitation of the radioactive gaseous and liquid effluents from radionuclide laboratories. The recommended values are based on a radiation exposure for members of a critical group in the population corresponding to 1% of the dose limit for individual members of the public as recommended by the ICRP. Based on these standards a classification of radionuclide laboratories is proposed. It is recommended to retain the present Dutch classification in A-, B-, C- and D-laboratories. The report contains appendices with detailed data about the transport routes of radionuclides in the environment and the subsequent irradiation of members of the public. (orig.)

Saturated Zone Colloid Transport

International Nuclear Information System (INIS)

H. S. Viswanathan

2004-01-01

This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, R col is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh, and ionic strength). These factors are folded into the distributions of R col that have been developed from field and experimental data collected under varying geochemical conditions with different colloid types and sizes. Attachment rate constants, k att , and detachment rate constants, k det , of colloids to the fracture surface have been measured for the fractured volcanics, and separate R col uncertainty distributions have been developed for attachment and detachment to clastic material and mineral grains in the alluvium. Radionuclides such as plutonium and americium sorb mostly (90 to 99 percent) irreversibly to colloids (BSC 2004 [DIRS 170025], Section 6.3.3.2). The colloid retardation factors developed in this analysis are needed to simulate the transport of radionuclides that are irreversibly sorbed onto colloids; this transport is discussed in the model report ''Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]). Although it is not exclusive to any particular radionuclide release scenario, this scientific analysis especially addresses those scenarios pertaining to evidence from waste-degradation experiments, which indicate that plutonium and americium may be irreversibly attached to colloids for the time scales of interest. A section of this report will also discuss the validity of using microspheres as analogs to colloids in some of the lab and field experiments used to obtain the colloid retardation factors. In addition, a small fraction of colloids travels with the groundwater without any significant retardation. Radionuclides irreversibly

Atmospheric transport modelling for the CTBT radionuclide network in routine operation and after the Fukushima releases; Atmosphaerische Transportmodellierung fuer das Radionuklidmessnetz zur Ueberwachung des Kernwaffenteststoppvertrages im Regelbetrieb und nach den Freisetzungen in Fukushima

Energy Technology Data Exchange (ETDEWEB)

Ross, J.O.; Ceranna, L.; Boennemann, C. [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Hannover (Germany). B4.3; Schlosser, C. [Bundesamt fuer Strahlenschutz (BfS), Freiburg (Germany). SW2.5

2014-01-20

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all types of nuclear explosions. For verification of compliance with Treaty the International Monitoring System (IMS) is being built up by the Provisional Technical Secretariat (PTS) of the CTBT-Organisation in Vienna. The IMS observes waveform signals (seismic, infrasound, hydroacoustic) of explosions and traces of radionuclides in the atmosphere to proof the nuclear character of an event. The International Data Centre (IDC) provides analysis products for the IMS data such as various event bulletins, radionuclide reports, and atmospheric transport modeling (ATM) results confining the possible source region of detected radionuclides. The judgment on the character of a suspicious event remains with the member states. The German National Data Centre for verification of CTBT is hosted by the Federal Institute for Geosciences and Natural Resources (BGR) in Hannover. The BGR operates four IMS stations (IS26, IS27, PS19, and AS35) and cooperates closely with the Federal Office for Radiation Protection (BfS) who operates the radionuclide station RN33 at mount Schauinsland and supports the NDC with radionuclide expertise. In response to the Fukushima accident caused by the large magnitude 9.0 Tohuku Earthquake and Tsunami the HSYSPLIT model driven by 0.5 degree NCEP data was used at the German NDC to simulate the primary transport pathways of potentially emitted radioisotopes. The analysis focuses on arrival times and dilution ratios at the radionuclide stations of the IMS. The arrival times were predicted correctly at most stations for ten days after the accident. Traces of the Fukushima emissions were detected at all IMS radionuclide stations on the Northern Hemisphere end of March. In April also some stations on the Southern Hemisphere detected some traces which passed the ITCZ. In respect to the CTBT context the influence of the Tohoku earthquake and the Fukushima emissions on the network capability to detect a

Modeling of the regional and global transport of radionuclides from the Kola NPP

Energy Technology Data Exchange (ETDEWEB)

Marchuk, G.I.; Aloyan, A.E.; Arutyunyan, V.O.; Louzan, P.I. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. for Numerical Mathematics; Bergman, R. [ed.] [Defence Research Establishment, Umeaa (Sweden). Div. of NBC Defence

2000-05-01

This Technical Report belongs to the INTAS project 96-1802: Assessment of potential risk of environmental radioactive contamination in northern Europe from terrestrial nuclear units in north-west Russia. The aim of this INTAS project is to assess the potential risk of environmental radioactive contamination from nuclear units in northwest Russia and resulting impacts on population and terrestrial ecosystems in the north. The work focuses mainly on airborne radioactive contamination, but some case studies also deal with accidental leakage from terrestrial nuclear sites to soil and coastal waters. The main aim in this technical report is to calculate and describe radioactive contamination levels in the Kola Peninsula resulting from a hypothetical accidental release from the Kola Nuclear Power Plant (KNPP). The method of assessment of radioactive contamination in the Kola Peninsula described here is based on the mathematical models developed at the Institute for Numerical Mathematics of the Russian Academy of Sciences (INM RAS). Model validation was performed several times on a wide variety of actual problems and case studies. The validation procedure indicated good capabilities in predicting the qualitative and quantitative contamination patterns resulting from the processes under consideration. Various scenarios reflecting typical meteorological conditions in a specific area are used in the numerical simulation. The conclusions resulting from analysis of such scenario calculations are of rather general character, and can be extrapolated in time provided that climate remains relatively stable. The employed 3D numerical model of radionuclide transport in the Northern hemisphere takes into account the interaction between boundary layers of the ocean and atmosphere, long term tracing of the radionuclides evolution in the atmosphere, their deposition on the earth surface, and migration in soil and sea water.

Transport and accumulation of radionuclides and stable elements in a Missouri River Reservoir

Science.gov (United States)

Callendar, Edward; Robbins, John A.

1993-01-01

Several long sediment cores from the Cheyenne River Embayment of Lake Oahe, a 250-km-long Missouri River reservoir in South Dakota, have been analyzed for radionuclides and stable elements. The combination of fine-scale sampling and rapid sedimentation produces radionuclide distributions that can be used to estimate the detailed chronology of particle transport processes in the Oahe reservoir system. A self-consistent and quantitative treatment of the 137Cs data suggests processes to which characteristic times may be associated. Times that characterize system-wide processes include (1) an integration time of several years reflecting retention of the sediment-bound tracer in regions within or external to the reservoir, (2) a relaxation time of approximately 15 years reflecting a decreasing rate of sediment accumulation ascribed to shoreline stabilization, (3) a time of a few months characterizing the breadth of riverine signatures in cores due to integration effects in the Cheyenne River system and deltaic deposits, and (4) times of a few years associated with propagation of riverine load signatures along the embayment. The distribution of total sedimentary arsenic confirms the validity of the variable sedimentation model. In 1977, a tailings retention facility was built at the Homestake Mine site, and the unrestricted input of As ceased. As a result of this remedial action, the concentration of sedimentary As decreased dramatically. In the upper section of the core, above the depth represented by the year 1976, the concentration of As decreases tenfold. In this same core the distribution of lithologically discriminating chemical elements, calcium and vanadium, relate to major flow events in the Cheyenne River basin. Because there is minimal diagenesis of chemical constituents in these rapidly accumulating sediments, stable element signatures, in addition to radiotracers, may be used to reconstruct hydrologic events in drainage basins that contribute sediment to

RANCH, Radionuclide Migration in Geological Media

International Nuclear Information System (INIS)

Patry, J.; Hadermann, J.

1991-01-01

1 - Description of problem or function: One-dimensional transport of radionuclide chains through layered geological media, taking into account longitudinal dispersion, convection and retention. 2 - Method of solution: Semi-analytical solution by Laplace transform. Convolution integrals. 3 - Restrictions on the complexity of the problem: Maximum 4 nuclides and 10 layers. Peclet number large compared to 1

Waste Form and Indrift Colloids-Associated Radionuclide Concentrations: Abstraction and Summary

International Nuclear Information System (INIS)

Aguilar, R.

2003-01-01

This Model Report describes the analysis and abstractions of the colloids process model for the waste form and engineered barrier system components of the total system performance assessment calculations to be performed with the Total System Performance Assessment-License Application model. Included in this report is a description of (1) the types and concentrations of colloids that could be generated in the waste package from degradation of waste forms and the corrosion of the waste package materials, (2) types and concentrations of colloids produced from the steel components of the repository and their potential role in radionuclide transport, and (3) types and concentrations of colloids present in natural waters in the vicinity of Yucca Mountain. Additionally, attachment/detachment characteristics and mechanisms of colloids anticipated in the repository are addressed and discussed. The abstraction of the process model is intended to capture the most important characteristics of radionuclide-colloid behavior for use in predicting the potential impact of colloid-facilitated radionuclide transport on repository performance

Waste Form and Indrift Colloids-Associated Radionuclide Concentrations: Abstraction and Summary

Energy Technology Data Exchange (ETDEWEB)

R. Aguilar

2003-06-24

This Model Report describes the analysis and abstractions of the colloids process model for the waste form and engineered barrier system components of the total system performance assessment calculations to be performed with the Total System Performance Assessment-License Application model. Included in this report is a description of (1) the types and concentrations of colloids that could be generated in the waste package from degradation of waste forms and the corrosion of the waste package materials, (2) types and concentrations of colloids produced from the steel components of the repository and their potential role in radionuclide transport, and (3) types and concentrations of colloids present in natural waters in the vicinity of Yucca Mountain. Additionally, attachment/detachment characteristics and mechanisms of colloids anticipated in the repository are addressed and discussed. The abstraction of the process model is intended to capture the most important characteristics of radionuclide-colloid behavior for use in predicting the potential impact of colloid-facilitated radionuclide transport on repository performance.

Transuranic radionuclides in the environment surrounding radioactive waste diposal sites, a bibliography

International Nuclear Information System (INIS)

Stoker, A.C.; Noshkin, V.E.; Wong, K.M.; Brunk, J.L.; Conrado, C.L.; Jones, H.E.; Kehl, S.; Stuart, M.L.; Wasley, L.M.; Bradsher, R.V.

1994-08-01

The purpose of this project was to compile a bibliography of references containing environmental transuranic radionuclide data. Our intent was to identify those parameters affecting transuranic radionuclide transport that may be generic and those that may be dependent on chemical form and/or environmental conditions (i.e. site specific). An understanding of the unique characteristics and similarities between source terms and environmental conditions relative to transuranic radionuclide transport and cycling will provide the ability to assess and predict the long term impact on man and the environment. An additional goal of our literature review, was to extract the ranges of environmental transuranic radionuclide data from the identified references for inclusion in a data base. Related to source term, these ranges of data can be used to calculate the dose to man from the radionuclides, and to perform uncertainty analyses on these dose assessments. In an attempt to gather relevant information about the transuranic radionuclides in a variety of environments, we conducted an extensive literature search. In our literature search we identified over 5700 potential written sources of information for review. In addition, we have identified many references which were not found through the literature searches, but which were known to contain useful data. A total of approximately 2600 documents were determined to contain information which would be useful for an in depth study of radionuclides in different environments. The journal articles, books, reports and other documents were reviewed to obtain the source term of the radionuclides studied. Most references containing laboratory study data were not included in our databases. Although these may contain valuable data, we were trying to compile references with information on the behavior of the transuranics in the specific environment being studied

Reactive Transport Modeling of the Yucca Mountain Site, Nevada

International Nuclear Information System (INIS)

G. Bodvarsson

2004-01-01

The Yucca Mountain site has a dry climate and deep water table, with the repository located in the middle of an unsaturated zone approximately 600 m thick. Radionuclide transport processes from the repository to the water table are sensitive to the unsaturated zone flow field, as well as to sorption, matrix diffusion, radioactive decay, and colloid transport mechanisms. The unsaturated zone flow and transport models are calibrated against both physical and chemical data, including pneumatic pressure, liquid saturation, water potential, temperature, chloride, and calcite. The transport model predictions are further compared with testing specific to unsaturated zone transport: at Alcove 1 in the Exploratory Studies Facility (ESF), at Alcove 8 and Niche 3 of the ESF, and at the Busted Butte site. The models are applied to predict the breakthroughs at the water table for nonsorbing and sorbing radionuclides, with faults shown as the important paths for radionuclide transport. Daughter products of some important radionuclides, such as 239 Pu and 241 Am, have faster transport than the parents and must be considered in the unsaturated zone transport model. Colloid transport is significantly affected by colloid size, but only negligibly affected by lunetic declogging (reverse filtering) mechanisms. Unsaturated zone model uncertainties are discussed, including the sensitivity of breakthrough to the active fracture model parameter, as an example of uncertainties related to detailed flow characteristics and fracture-matrix interaction. It is expected that additional benefits from the unsaturated zone barrier for transport can be achieved by full implementation of the shadow zone concept immediately below the radionuclide release points in the waste emplacement drifts

Radiometric characterisation supports, burnup credit, safeguards and radionuclide inventory determination for spent fuel transport, storage and disposal

International Nuclear Information System (INIS)

Chesterman, A.S.; Clapham, M.J.; Gardner, N.

1999-01-01

Spent nuclear fuel characterisation measurements play an essential role in a range of fuel handling activities. In particular, they are necessary to support the application of burnup credit to the transport of spent fuel, to detect diversion of safeguarded nuclear material and to determine the radionuclide inventory of materials destined for final disposal. To apply measurements to these activities the measurement procedures need to be approved by the relevant regulatory bodies. Often key to the measurement procedures is the method of instrument system calibration and what a priori data is acceptable to aid the measurement process. Discussion of these, pertinent to the three areas of application mentioned above, is presented with suggestions of alternative approaches where considered appropriate. (author)

SITE-SCALE SATURATED ZONE TRANSPORT

International Nuclear Information System (INIS)

S. KELLER

2004-01-01

This work provides a site-scale transport model for calculating radionuclide transport in the saturated zone (SZ) at Yucca Mountain, for use in the abstractions model in support of ''Total System Performance Assessment for License Application'' (TSPA-LA). The purpose of this model report is to provide documentation for the components of the site-scale SZ transport model in accordance with administrative procedure AP-SIII.10Q, Models. The initial documentation of this model report was conducted under the ''Technical Work Plan For: Saturated Zone Flow and Transport Modeling and Testing'' (BSC 2003 [DIRS 163965]). The model report has been revised in accordance with the ''Technical Work Plan For: Natural System--Saturated Zone Analysis and Model Report Integration'', Section 2.1.1.4 (BSC 2004 [DIRS 171421]) to incorporate Regulatory Integration Team comments. All activities listed in the technical work plan that are appropriate to the transport model are documented in this report and are described in Section 2.1.1.4 (BSC 2004 [DIRS 171421]). This report documents: (1) the advection-dispersion transport model including matrix diffusion (Sections 6.3 and 6.4); (2) a description and validation of the transport model (Sections 6.3 and 7); (3) the numerical methods for simulating radionuclide transport (Section 6.4); (4) the parameters (sorption coefficient, Kd ) and their uncertainty distributions used for modeling radionuclide sorption (Appendices A and C); (5) the parameters used for modeling colloid-facilitated radionuclide transport (Table 4-1, Section 6.4.2.6, and Appendix B); and (6) alternative conceptual models and their dispositions (Section 6.6). The intended use of this model is to simulate transport in saturated fractured porous rock (double porosity) and alluvium. The particle-tracking method of simulating radionuclide transport is incorporated in the finite-volume heat and mass transfer numerical analysis (FEHM) computer code, (FEHM V2.20, STN: 10086

Global deposition of fallout radionuclides and their dietary intake

International Nuclear Information System (INIS)

Morisawa, Shinsuke

1993-01-01

Japanese foods depend largely on foreign countries and domestic food supply now is no more than 30 percents if feedstuffs for live-stocks are included. Therefore not only ecological/natural but also social, e.g., human activities related, transportation of fallout radionuclides are to be taken into accounts for estimation of baseline internal irradiation dose and health risks of Japanese peoples through dietary intake of radionuclides. In this study, mathematical model is developed and examined for practical application on estimating Japanese dietary intake level of fallout strontium-90, which is accumulated in various kinds of foodstuffs and is transported to Japan associated with worldwide trades of foods, under appropriate limitations such that direct deposition on plants and seafood intake pathways are not evaluated. Deposition of strontium-90 onto the surface soil was simulated using the model, the compartment model described by a set ordinary differential equations, and the estimates were examined by comparing them with the observed data colleted and complied by the global scale environmental monitoring networks. Sensitivity analysis is also practised to find possible reduction of dietary intake of fallout radionuclides and the related potential health risks. (author)

Preliminary rate expressions for analysis of radionuclide migration resulting from fluid flow through jointed media

Energy Technology Data Exchange (ETDEWEB)

Erickson, K.L.

1979-01-01

A theoretical and experimental basis is being developed for analysis of radionuclide transport in jointed geologic media. Batch equilibration and rate experiments involving samples of Eleana argillite and tertiary silicic tuffs in contact with solutions containing Cs, Sr, or Pm indicated that most radionuclide sorption was associated with the surfaces of very small intergranular regions and that the rate of sorption was controlled by diffusion of the nuclides into such regions. Based on these experimental results, the continuity equations for radionuclides in the mobile and immobile phases were reduced to a model analogous to Rosen's equations for packed beds and were solved similarly. Using the model and experimental data, limited radionuclide transport analyses were made which indicated that important parameters controlling transport include the intergranular porosity and nuclide penetration depth, fracture plate spacing and length, fluid velocity and sorption distribution coefficient. Many of these parameters represent physical quantities or processes which can be quantified in the laboratory. However, fluid velocities and fracture plate spacings and lengths must be obtained from the field, and methods must be developed to establish reliable bounds for such field-determined parameters.

Preliminary rate expressions for analysis of radionuclide migration resulting from fluid flow through jointed media

International Nuclear Information System (INIS)

Erickson, K.L.

1979-01-01

A theoretical and experimental basis is being developed for analysis of radionuclide transport in jointed geologic media. Batch equilibration and rate experiments involving samples of Eleana argillite and tertiary silicic tuffs in contact with solutions containing Cs, Sr, or Pm indicated that most radionuclide sorption was associated with the surfaces of very small intergranular regions and that the rate of sorption was controlled by diffusion of the nuclides into such regions. Based on these experimental results, the continuity equations for radionuclides in the mobile and immobile phases were reduced to a model analogous to Rosen's equations for packed beds and were solved similarly. Using the model and experimental data, limited radionuclide transport analyses were made which indicated that important parameters controlling transport include the intergranular porosity and nuclide penetration depth, fracture plate spacing and length, fluid velocity and sorption distribution coefficient. Many of these parameters represent physical quantities or processes which can be quantified in the laboratory. However, fluid velocities and fracture plate spacings and lengths must be obtained from the field, and methods must be developed to establish reliable bounds for such field-determined parameters

Radionuclide adsorption characteristics around coastal water

International Nuclear Information System (INIS)

Song, Young Il; Chung, Yang Geun; Hong, Sung Yul; Lee, Gab Bock

1999-01-01

The adsorption capacity of radionuclides onto suspended sediment was experimented on each of the coastal seawater sampled around the Kori and the Wolsung nuclear power plant. During the experiment the quantity and size fraction of suspended sediment were adjusted and the seawater and sediment chemistry is approximated to the expected field condition. Because the sorption capacity depends on the specific minerals, ocean chemistry and radionuclide involved, it is necessary to analyze sediment mineralogy. Clay mineral is dominant in seabed mineral and suspended sediment as the result of x-ray diffraction. Radionuclide sorbed to silty-clay mineral can be rather transported to ocean than scavenged to seabed because of low quantity and fine grained suspended sediment in the coast around the Kori and the Wolsung. The result of adsorption examinations shows that 139 Ce and 51 Cr and 110m Ag are strongly sorbed to suspended particle, while 137 Cs is less sorbed and 60 Co uptake is varied with experiment condition, which can be inferred from various biological factors. (author). 9 refs., 2 tabs., 7 figs

Transfer factors for assessing the dose from radionuclides in agricultural products

International Nuclear Information System (INIS)

Ng, Y.C.; Colsher, C.S.; Thompson, S.E.

1979-01-01

Transfer factors to predict the environmental transport of radionuclides through terrestrial foodchains to man were derived from the literature for radionuclides associated with the nuclear fuel cycle. We present updated transfer coefficients to predict the concentration of a radionuclide in cow's milk and other animal products and concentration factors (CF) to predict the concentration in a food or feed crop from that in soil. Where possible we note the variation of the transfer factor with physical and chemical form of the radionuclide and environmental factors, and characterize the distribution and uncertainty in the estimate. The updated transfer factors are compared with those listed in regulatory guides. The new estimates lead to recommended changes (both increases and decreases) in the listed transfer coefficients for milk and meat and to the suggested practice of adopting multiple soil-to-plant CF's that vary with the type of crop and soil in the place of a single generic CF to predict the concentration of a radionuclide in a crop from that in soil. The updated transfer factors will be useful to assess the dose from radionuclides released from nuclear facilities and evaluating compliance with regulations governing the release of radionuclides

Review of radionuclide source terms used for performance-assessment analyses

International Nuclear Information System (INIS)

Barnard, R.W.

1993-06-01

Two aspects of the radionuclide source terms used for total-system performance assessment (TSPA) analyses have been reviewed. First, a detailed radionuclide inventory (i.e., one in which the reactor type, decay, and burnup are specified) is compared with the standard source-term inventory used in prior analyses. The latter assumes a fixed ratio of pressurized-water reactor (PWR) to boiling-water reactor (BWR) spent fuel, at specific amounts of burnup and at 10-year decay. TSPA analyses have been used to compare the simplified source term with the detailed one. The TSPA-91 analyses did not show a significant difference between the source terms. Second, the radionuclides used in source terms for TSPA aqueous-transport analyses have been reviewed to select ones that are representative of the entire inventory. It is recommended that two actinide decay chains be included (the 4n+2 ''uranium'' and 4n+3 ''actinium'' decay series), since these include several radionuclides that have potentially important release and dose characteristics. In addition, several fission products are recommended for the same reason. The choice of radionuclides should be influenced by other parameter assumptions, such as the solubility and retardation of the radionuclides

Geotrap: radionuclide migration in geologic, heterogeneous media. Summary of accomplishments

International Nuclear Information System (INIS)

2002-01-01

GEOTRAP - the OECD/NEA Project on Radionuclide Migration in Geologic, Heterogeneous Media - was carried out in the context of site evaluation and safety assessment of deep repository systems for long-lived radioactive waste. The project was created in 1996 with the aim of developing an understanding of, and modelling capability for, potential radionuclide migration. This report provides an overview of the project's main findings and accomplishments over its five-year life. This summary should help make the valuable information collected and generated by the GEOTRAP project accessible to a wide readership both within and outside the radioactive waste community.It is a reflection of the careful attention paid by this community to the question of radionuclide transport. (authors)

MARFA version 3.2.2 user's manual: migration analysis of radionuclides in the far field

Energy Technology Data Exchange (ETDEWEB)

Painter, Scott; Mancillas, James (Center for Nuclear Waste Regulatory Analyses, Southwest Research Inst., San Antonio, TX (United States))

2009-12-15

The computer code Migration Analysis of Radionuclides in the Far Field (MARFA) uses a particle-based Monte Carlo method to simulate the transport of radionuclides in a sparsely fractured geological medium. Transport in sparsely fractured rock is of interest because this medium may serve as a barrier to migration of radionuclides to the accessible environment. The physical processes represented in MARFA include advection, longitudinal dispersion, Fickian diffusion into an infinite or finite rock matrix, equilibrium sorption, decay, and in-growth. Multiple non-branching decay chains of arbitrary length are supported. This document describes the technical basis and input requirements for MARFA Version 3.2.2. MARFA Version 3.2 included new capabilities to accommodate transient flow velocities and sorption parameters, which are assumed to be piecewise constant in time. Version 3.2.1 was a minor change from Version 3.2 to allow a more convenient input format for sorption information. New capabilities in Version 3.2.2 include an option to specify a non-zero start time for the simulation, an optional input parameter that decreases the amount of retention within a single fracture because of flow channeling, and an alternative method for sampling the radionuclide source. MARFA uses the particle on random streamline segment algorithm/Painter et al. 2006/, a Monte Carlo algorithm combining time-domain random walk methods with pathway stochastic simulation. The algorithm uses non-interacting particles to represent packets of radionuclide mass. These particles are moved through the system according to rules that mimic the underlying physical transport and retention processes. The set of times required for particles to pass through the geological barrier are then used to reconstruct discharge rates (mass or activity basis). Because the algorithm uses non-interacting particles, the transport and retention processes are limited to those that depend linearly on radionuclide

Effects of humic substances on the migration of radionuclides: complexation and transport of actinides. First technical progress report (work period 01.97 - 12.97)

International Nuclear Information System (INIS)

Buckau, G.

1998-08-01

The present report describes progress within the first year of the EC-project 'Effects of Humic Substances on the Migration of Radionuclides: Complexation and Transport of Actinides'. The project is conducted within the EC-Cluster 'Radionuclide Transport/Retardation Processes'. Contrary to formal requirements of the Commission, this report with a great deal of detail is established already after one year of project work. It is scheduled to be followed by a second technical progress report covering the second year of the project. In agreement with the contractual obligations a final report of similar technical detail will also be generated. The report contains an executive summary written by the coordinator (FZK/INE) with strong support from the other three task leaders (BGS, CEA-SGC and RMC-E). More detailed results are given by individual contributions of the project partners in 13 annexes. In the executive summary report the origin of results presented is given, also serving as guidance for finding more detailed results in the annexes. Not all results are discussed or referred to in the executive summary report and thus readers with a deeper interest also need to consult the annexes. (orig.)

Radionuclide toxicity

International Nuclear Information System (INIS)

Galle, P.

1982-01-01

The aim of this symposium was to review the radionuclide toxicity problems. Five topics were discussed: (1) natural and artificial radionuclides (origin, presence or emission in the environment, human irradiation); (2) environmental behaviour of radionuclides and transfer to man; (3) metabolism and toxicity of radionuclides (radioiodine, strontium, rare gas released from nuclear power plants, ruthenium-activation metals, rare earths, tritium, carbon 14, plutonium, americium, curium and einsteinium, neptunium, californium, uranium) cancerogenous effects of radon 222 and of its danghter products; (4) comparison of the hazards of various types of energy; (5) human epidemiology of radionuclide toxicity (bone cancer induction by radium, lung cancer induction by radon daughter products, liver cancer and leukaemia following the use of Thorotrast, thyroid cancer; other site of cancer induction by radionuclides) [fr

Experimental and modelling studies of radionuclide migration from contaminated groundwaters

International Nuclear Information System (INIS)

Tompkins, J. A.; Butler, A. P.; Wheater, H. S.; Shaw, G.; Wadey, P.; Bell, J. N. B.

1994-01-01

Lysimeter-based studies of radionuclide uptake by winter wheat are being undertaken to investigate soil-to-plant transfer processes. A five year multi-disciplinary research project has concentrated on the upward migration of contaminants from near surface water-tables and their subsequent uptake by a winter wheat crop. A weighted transfer factor approach and a physically based modelling methodology, for the simulation and prediction of radionuclide uptake, have been developed which offer alternatives to the traditional transfer factor approach. Integrated hydrological and solute transport models are used to simulate contaminant movement and subsequent root uptake. This approach enables prediction of radionuclide transport for a wide range of soil, plant and radionuclide types. This paper presents simulated results of 22 Na plant uptake and soil activity profiles, which are verified with respect to lysimeter data. The results demonstrate that a simple modelling approach can describe the variability in radioactivity in both the harvested crop and the soil profile, without recourse to a large number of empirical parameters. The proposed modelling technique should be readily applicable to a range of scales and conditions, since it embodies an understanding of the underlying physical processes of the system. This work constitutes part of an ongoing research programme being undertaken by UK Nirex Ltd., to assess the long term safety of a deep level repository for low and intermediate level nuclear waste. (author)

Modeling of the geochemical behaviour and of the radionuclide transport in the presence of colloids

International Nuclear Information System (INIS)

Van der Lee, Jan

1997-01-01

Over the past ten years, colloids have been introduced in the already complex subject of waste storage safety analysis. They are indeed often considered as rapid carriers for otherwise insoluble radioactive elements, and therefore potentially decrease the effective barrier function of the geological rock surrounding the waste. The problem is therefore to understand colloid behaviour and quantify their stability and reactivity with respect to the radionuclides. The subject reveals three different levels of phenomena: the geochemical mechanisms, the micro-physical and electrostatic behaviour of colloids and the transport mechanisms. The topics of this thesis therefore cover a wide range of disciplines, such as geochemistry, radiochemistry, physics, hydrogeology, mathematics and computer science. Given the complexity of the subject, only strongly simplified models are used for safety assessment including the impact of colloids. Henceforth, the objective of this study is to provide a comprehensive theoretical basis for modelling the impact of colloids according to a deterministic approach, in the hope to pave the road towards predictive modelling of a waste repository performance. This thesis is the result of work carried out in different European Community projects in the framework of the fourth R and D program on 'Management and Storage of Radioactive Waste'. part A, task 4, 'Disposal of Radioactive Waste'. Grateful use has been made of many chemical and hydrogeological experiments carried out by many different laboratories all over Europe. The main results can be classified according to three principal topics: - geochemistry and the chemical behaviour of actinides, lanthanides and fission products; - retention mechanisms of colloidal particles; - transport mechanism in geological medium. The first topic is fundamental: geochemistry forms the basis of e.g. the retention model for aqueous and colloidal species. The principal result of this topic is

The radionuclide migration experiment - overview of investigations 1985 - 1990

International Nuclear Information System (INIS)

Frick, U.; McKinley, I.G.; Baeyens, B.; Bradbury, M.H.; Eikenberg, J.; Heer, W.; Hoehn, E.; Smith, P.A.; Alexander, W.R.; Bossart, P.; Buehler, C.; Fierz, T.

1992-03-01

This paper provides an overview of the investigations conducted from 1985 to 1990 as a part of the radionuclide migration experiment which is currently in progress in the Nagra underground research laboratory at the Grimsel pass in the Central Swiss Alps. The major aims of the project are (1) to test the extrapolation of laboratory sorption data to field conditions, (2) to analyse retardation processes in a fractured rock, (3) to improve and develop the necessary methodologies for site characterization and (4) to test existing geochemical, hydrodynamic, and solute transport models or their associated data bases. Field and modeling work are complemented by an extensive laboratory support programme. The Grimsel migration experiment demonstrates conclusively how the combined efforts of modeling, laboratory and field investigations can substantially widen the understanding of radionuclide transport in a geological environment. (author) figs., tabs., refs

Saturated Zone Colloid Transport

Energy Technology Data Exchange (ETDEWEB)

H. S. Viswanathan

2004-10-07

This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, R{sub col} is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh, and ionic strength). These factors are folded into the distributions of R{sub col} that have been developed from field and experimental data collected under varying geochemical conditions with different colloid types and sizes. Attachment rate constants, k{sub att}, and detachment rate constants, k{sub det}, of colloids to the fracture surface have been measured for the fractured volcanics, and separate R{sub col} uncertainty distributions have been developed for attachment and detachment to clastic material and mineral grains in the alluvium. Radionuclides such as plutonium and americium sorb mostly (90 to 99 percent) irreversibly to colloids (BSC 2004 [DIRS 170025], Section 6.3.3.2). The colloid retardation factors developed in this analysis are needed to simulate the transport of radionuclides that are irreversibly sorbed onto colloids; this transport is discussed in the model report ''Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]). Although it is not exclusive to any particular radionuclide release scenario, this scientific analysis especially addresses those scenarios pertaining to evidence from waste-degradation experiments, which indicate that plutonium and americium may be irreversibly attached to colloids for the time scales of interest. A section of this report will also discuss the validity of using microspheres as analogs to colloids in some of the lab and field experiments used to obtain the colloid retardation factors. In addition, a small fraction of colloids travels with the groundwater without any significant

A review of the role of colloids in the release and transport of radionuclides in the near and far field. Pt. 3

International Nuclear Information System (INIS)

Tipping, E.; Higgo, J.J.W.

1992-01-01

The role of colloids in the release and transport of radionuclides in the near and far field is discussed and DOE and Nirex funded work is compared with relevant studies by other workers. Gaps in the DOE and Nirex programmes are identified and suggestions for further research are made. This is Part 3 of a three-part review. Part 1 reviews fundamental theory and DOE and Nirex funded work and Part 2 is a comprehensive bibliography (with abstracts). (Author)

Study of test methods for radionuclide migration in aerated zone

International Nuclear Information System (INIS)

Li Shushen; Guo Zede; Wang Zhiming

1993-01-01

Aerated zone is an important natural barrier against transport of radionuclides released from disposal facilities of LLRW. This paper introduces study methods for radionuclide migration in aerated zone, including determination of water movement, laboratory simulation test, and field tracing test. For one purpose, results obtained with different methods are compared. These methods have been used in a five-year cooperative research project between CIRP and JAERI for an establishment of methodology for safety assessment on shallow land disposal of LLRW

Characterization of Discharge Areas of Radionuclides Originating From Nuclear Waste Repositories

Science.gov (United States)

Marklund, L.; Xu, S.; Worman, A.

2009-05-01

If leakages in nuclear waste repositories located in crystalline bedrock arise, radionuclides will reach the biosphere and cause a risk of radiological impact. The extent of the radiological impact depends on in which landscape elements the radionuclides emerge. In this study, we investigate if there are certain landscape elements that generally will act as discharge areas for radionuclides leaking from subsurface deposits. We also characterize the typical properties that distinguish these areas from others. In humid regions, landscape topography is the most important driving force for groundwater flow. Because groundwater is the main transporting agent for migrating radionuclides, the topography will determine the flowpaths of leaking radionuclides. How topography and heterogeneities in the subsurface affect the discharge distribution of the radionuclides is therefore an important scope of this study. To address these issues, we developed a 3-D transport model. Our analyses are based on site-specific data from two different areas in Sweden, Forsmark, Uppland, and Oskarshamn, Småland. The Swedish Nuclear Waste Management Company (SKB) has selected these two areas as candidate areas for a deep repository of nuclear waste and the areas are currently subject to site investigations. Our results suggest that there are hot-spots in the landscape i.e. areas with high probability of receiving large amounts of radionuclides from a leaking repository of nuclear waste. The hot-spots concentrate in the sea, streams, lakes and wetlands. All these elements are found at lower elevations in the landscape. This pattern is mostly determined by the landscape topography and the locations of fracture zones. There is a relationship between fracture zones and topography, and therefore the importance of the topography for the discharge area distribution is not contradicted by the heterogeneity in the bedrock. The varieties of landscape elements which have potential for receiving

Radionuclide distributions and migration mechanisms at shallow land burial sites

International Nuclear Information System (INIS)

Kirby, L.J.; Toste, A.P.; Thomas, C.W.; Rickard, W.H.; Nielson, H.L.; Campbell, R.M.; McShane, M.C.; Wilkerson, C.L.; Robertson, D.E.

1991-02-01

During the past several years, Pacific Northwest Laboratory (PNL) has conducted research at the Maxey Flats Disposal Site (MFDS) for the US Nuclear Regulatory Commission (NRC). This work has identified the spectrum of radionuclides present in the waste trenches, determined the processes that were occurring relative to degradation of radioactive material within the burial trenches, determined the chemical and physical characteristics of the trench leachates and the chemical forms of the leached radionuclides, determined the mobility of these radionuclides, investigated the subsurface and surface transport processes, determined the biological uptake by the native vegetation, developed strategies for environmental monitoring, and investigated other factors that influence the long-term fate of the radionuclide inventory at the disposal site. This report is a final summary of the research conducted by PNL and presents the results and discussions relative to the above investigative areas. 45 refs., 31 figs., 17 tabs

A strategy for validation a concept model for radionuclide migration in the saturated zone beneath Yucca Mountain

International Nuclear Information System (INIS)

Robinson, B.A.

1994-01-01

A conceptual model for radionuclide migration in the saturated zone beneath Yucca Mountain is presented. The available hydrologic data from the site is compiled to present a qualitative picture of transport of radionuclides horizontally within the first 100-200 m of the saturated zone. The transport model consists of flow within fractures and interchange of dissolved species between the fractures and surrounding matrix blocks via molecular diffusion. A parametric study illustrates that at the groundwater conditions expected to exist in the saturated zone, radionuclide will have ample time to diffuse fully within the matrix blocks. The result is a predicted solute transport time several orders of magnitude greater than the groundwater travel time (GWTT). To validate this model, a suite of interwell tracer tests are proposed at various flow rates and with conservative and sorbing species. Numerical simulations show that these tests will allow us to discriminate between a matrix diffusion model and a more conventional continuum transport model. (author) 8 figs., tabs., 35 refs

The Q system and the radiotoxicity of the radionuclides

International Nuclear Information System (INIS)

Hamard, J.

1989-01-01

The first edition of the International Atomic Energy Agency (IAEA) Regulations for the safe transport of radioactive materials was issued in 1962. The transported radionuclides were distributed into three groups according to their radiotoxicity. The radiotoxicity was evaluated by means of an injury index taking into account the dose equivalent received following a mean accident by incorporation, by inhalation, by ingestion or by wound. The 1962 regulations introduced the terminology of type A and type B packages and the nature of mean accident during which a person can incorporate an activity equal to 1/10 6 of the activity contained in the type A package. The reference dose equivalent was equal to 1/4 of the annual limit of equivalent dose for workers (in the following, they use dose in place of equivalent dose). Following these criteria the transported radionuclides were distributed into three groups of radiotoxicity: Very high - High - Low or moderate. The nature of special form materials and of low specific activity materials (LSA) was also introduced by reference to the incorporation of mass superior to 1 mg

Particle Tracking Model and Abstraction of Transport Processes

International Nuclear Information System (INIS)

Robinson, B.

2000-01-01

The purpose of the transport methodology and component analysis is to provide the numerical methods for simulating radionuclide transport and model setup for transport in the unsaturated zone (UZ) site-scale model. The particle-tracking method of simulating radionuclide transport is incorporated into the FEHM computer code and the resulting changes in the FEHM code are to be submitted to the software configuration management system. This Analysis and Model Report (AMR) outlines the assumptions, design, and testing of a model for calculating radionuclide transport in the unsaturated zone at Yucca Mountain. In addition, methods for determining colloid-facilitated transport parameters are outlined for use in the Total System Performance Assessment (TSPA) analyses. Concurrently, process-level flow model calculations are being carrier out in a PMR for the unsaturated zone. The computer code TOUGH2 is being used to generate three-dimensional, dual-permeability flow fields, that are supplied to the Performance Assessment group for subsequent transport simulations. These flow fields are converted to input files compatible with the FEHM code, which for this application simulates radionuclide transport using the particle-tracking algorithm outlined in this AMR. Therefore, this AMR establishes the numerical method and demonstrates the use of the model, but the specific breakthrough curves presented do not necessarily represent the behavior of the Yucca Mountain unsaturated zone