Concept and Applicability of Sorption Distribution Coefficient in the Radionuclide Transport Model

A well-designed environmental monitoring plan is essential for safety of uranium mining and processing operations. Evaluating the possible uncertainties in a numerical model helps in enhancing the model output and also increases the reliability over the model results. For a radionuclide transport model, distribution co-efficient is a sensitive parameter and major source of uncertainty in results. In this study, an approach to quantify input source of uncertainty of distribution co-efficient in an engineered tailings pond in Northern Karnataka, India has been carried out. Probabilistic analysis such as Response Surface Method and Monte Carlo Simulation are used to propagate uncertainty. This study considers uncertainty associated with intrinsic heterogeneity of natural systems and estimates the probability that dose rate value through drinking water pathway around the tailings pond exceeds the WHO guidelines for drinking water. The radionuclides considered in this study are 238U, 234U, 230Th and 226Ra. This study can be used to study the impact of distribution co-efficient on the radionuclide transport model.Key words: Numerical modelling, Tailings pond area, Uranium mining, Uncertainty, &#160;Distribution coefficient&#160;

Download Full-text

Radionuclide transport model for risk evaluation of high-level radioactive waste in Northwestern China

Human and Ecological Risk Assessment An International Journal ◽

10.1080/10807039.2017.1361811 ◽

2017 ◽

Vol 23 (8) ◽

pp. 2017-2032 ◽

Cited By ~ 3

Author(s):

Xiaoyuan Cao ◽

Litang Hu ◽

Jinsheng Wang ◽

Jingrui Wang

Keyword(s):

Radioactive Waste ◽

Risk Evaluation ◽

Transport Model ◽

Northwestern China ◽

Radionuclide Transport ◽

High Level Radioactive Waste ◽

High Level

Download Full-text

Data Reduction for Radionuclide Transport Codes Used in Performance Assessments: An Example of Simplification Process

MRS Proceedings ◽

10.1557/proc-506-797 ◽

1997 ◽

Vol 506 ◽

Cited By ~ 1

Author(s):

B. Dverstorp ◽

B. Mendes ◽

A. Pereira ◽

B. Sundström

Keyword(s):

Data Reduction ◽

Transport Model ◽

Computer Experiments ◽

Simple Calculation ◽

Radionuclide Transport ◽

Transport Pathway ◽

Transport Models ◽

Transport Pathways ◽

Flow Parameters ◽

Spatially Varying

ABSTRACTThe input data required for transport models for use in long-term risk assessments of repositories for radioactive waste, in geological media, are intrinsic to the performance of the models. The flow parameters utilized in these models typically come from 2 or 3D hydro-geological calculations done in a prior phase of an assessment. This paper examines some of the standard simplifications introduced when hydrogeological data are reduced to ID as is often required for radionuclide transport models. Two key aspects of data reduction are the determination of average properties of fractured media between and along transport pathways. To quantify possible errors associated with these reduction procedures, two computer experiments have been done. We show that the use of effective flow parameters, representing the average properties of a set of independent transport pathways, in a 1 D radionuclide transport model can result in an underestimation of peak releases by one order of magnitude or more. This result is valid for short-lived nuclides whenever retardation is an important factor. On the other hand, averaging of spatially varying transport properties along a transport pathway may lead to unjustified conservatism. A simple calculation example using Monte Carlo technique, shows that a model that does not take into account spatially varying retardation properties along the transport pathways may overestimate peak release rates by several orders of magnitude. We conclude that more sophisticated transport models taking into account available hydrogeological information on spatial variability are needed to fully understand the potential errors associated with consequence calculations in the performance assessment

Download Full-text

Distributed modeling of radionuclide washing out from the watersheds in solute and with suspended sediments: case studies Abukuma River, Fukushima Prefecture and Pripyat – Dnieper river system, Ukraine

10.5194/egusphere-egu2020-19250 ◽

2020 ◽

Author(s):

Mark Zheleznyak ◽

Oleksandr Pylypenko ◽

Sergii Kivva ◽

Kazuyuki Sakuma ◽

Yasunori Igarashi ◽

...

Keyword(s):

Transport Model ◽

Suspended Sediments ◽

Transport Processes ◽

Computational Time ◽

Type Model ◽

Distributed Data ◽

Radionuclide Transport ◽

Fukushima Prefecture ◽

Distributed Models

The measurements of&#160; 137Cs concentration in the rivers of Fukushima prefecture demonstrate the more significant role of the fluxes of 137Cs adherent to the suspended sediments in comparison with the rivers contaminated after the Chernobyl accident. Therefore the forecasting of&#160; &#160;137Cs&#160; concentration during the floods requires to use the models of radionuclide wash-off from the watersheds with sediments.Comprehensive modeling of radionuclide transport processes could be provided on the basis of the physically-based distributed models of hydrological and sediments transport processes. Such distributed models can describe soil erosion and sedimentation processes, as also exchange of the radionuclides between solute, suspended sediment and upper soil level. &#160;We developed such type .model DSHVM-R based on the distributed hydrological- sediment transport model DHSVM of Washington University.&#160; The model implementation for the experimental plots in Fukushima prefecture demonstrated a good possibility of the model for the analyses on the influence of the steepness of the watershed slopes and the intensity of the rainfall in the increased role of particulate 137Cs transport. &#160;From another side,&#160; the implementation of such a model for large river watershed required too large computational time and significant efforts for processing of the large sets of the distributed data still not available for all watersheds.We developed model RETRACE _RS &#160;that combines the simplicity of the watershed empirical models based on the washing -out coefficient approach with the possibility to use geographically distributed data of the radioactive fallout and &#160;GIS layers for rivernets. The model RETRACE_RS is an extension of the model RETRACE _R&#160; (Zheleznyak et al, 2010),&#160; which code is integrated into the Hydrological Dispersion&#160; Module of the Decision Support System RODOS.&#160; &#160;RETRACE_R is based on the assumptions that the rate of the radionuclide wash- off from each elementary grid cell of the watershed can be calculated from precipitation rate and density of deposition in this cell through the &#8220;wash-off&#8221; coefficient Kw; and that the radionuclides washed out from the cell are transported without time delay to the nearest river channel cell - to the grid element of the 1-D river model RIVTOX as lateral inflow. In RETRACE _RS the possibility of RETRACE_R to simulate washing -out of the radionuclides from watershed to river in solute was extended by the fluxes of the particulate radionuclide transport calculated via the &#8220; washing out coefficient for particulate radionuclide transport &#8221; -Kss. The formula to calculate Kss values is based on the empirical relations for the particulate &#160;137Cs transport in the rivers of Fukushima prefecture ( Sakuma et al, 2019). The model was tested on the basis of the measurements of 137Cs concentration in Abukuma river during the high floods in 2018-2019. The modeling system RETRACE_RS&#160; - RIVTOX was validated also on the basis of the data sets of radionuclide transport in the Pripyat and Dnieper rivers. The system is testing for the prediction of aquatic radionuclide transport from the Chernobyl NPP area to the&#160; Kyiv region during the extreme floods.&#160;

Download Full-text

Practical Availability of Radionuclide Transport Model based on the Interaction among Radionuclide, Colloid and Rock

Transactions of the Atomic Energy Society of Japan ◽

10.3327/taesj2002.2.460 ◽

2003 ◽

Vol 2 (4) ◽

pp. 460-468

Author(s):

Susumu KUROSAWA ◽

Shinzo UETA ◽

Mikazu YUI ◽

Hiroyasu KATO ◽

Kenichi HAYASHI ◽

...

Keyword(s):

Transport Model ◽

Radionuclide Transport ◽

Model Based

Download Full-text

Radionuclide Transport Modeling of Diffusion Cell Experiments Specific to a Backfill Barrier in a Salt Repository

MRS Proceedings ◽

10.1557/proc-26-681 ◽

1983 ◽

Vol 26 ◽

Author(s):

Harold M. Anderson ◽

John M. Pietz ◽

Douglas M. Smith

Keyword(s):

Transport Model ◽

Finite Difference Methods ◽

Solution Technique ◽

Radionuclide Transport ◽

Diffusion Cell ◽

Radionuclide Migration ◽

Integral Equation Approach ◽

Cell Data ◽

Diffusion Cell Experiments

ABSTRACTExperimental radionuclide migration diffusion cell data have been collected as part of the WIPP Waste Package Performance Program. This data was collected under conditions approximating geologic isolation of a backfill barrier in a salt repository. The experiments are designed to aid in the evaluation of engineered backfill barriers.This paper describes a radionuclide transport model designed to aid interpreting experimental diffusion cell migration data and eventually to simulate the long-term effectiveness of the backfill barrier in a salt repository. The model is designed to test a variety of expressions representative of potential mechanisms for retardation within the backfill for the best-fit with experimental data. From the comparison, the aim is to select the appropriate mechanism from the host of potential mechanisms for retardation. The model employs a novel integral equation approach to the solution of the transport equation with nonlinear retardation terms. The solution technique used in this model is a semi-analytical, iterative method for the general nonlinear problem. It is felt the technique offers improved computational efficiency over comparable finite difference methods.Comparisons between experimental migration diffusion cell data and the model predictions are presented in this paper. Tentative conclusions concerning the importance of the retardation mechanism to radionuclide transport in the backfill barrier will be drawn.

Download Full-text