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JAEA Reports

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

*;

JNC-TN8400 2001-027, 131 Pages, 2001/11

JNC-TN8400-2001-027.pdf:0.8MB

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 geostastical 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 geostastical 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 geostastical 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.

JAEA Reports

Nuclide migration uncertainty study in channel network model approximation

; *

JNC-TN8400 2001-010, 25 Pages, 2001/03

JNC-TN8400-2001-010.pdf:0.65MB

Performance assessment in geosphere for the JNC's 2nd progress report was based on nuclide migration calculation results by discrete fracture network model. The channel network model approximated from fracture network model with considering fracture connectivity was applied for nuclide migration analysis, since fracture network model had too large data to calculate nuclide migration. However, there are many options in the process of approximation from fracture network model to channel network model. In case of analyzing nuclide migration for above report, so-called "base case", one option was chosen from many options, arbitrarily. In this report, the sensitivity of these options to nuclide migration calculation results was studied. As a result, there was no significant impact to nuclide migration although connectivity of channel and flow characteristics of the model slightly changed among different options. Based on above studies, we concluded that an option used for the base case was appropriate.

JAEA Reports

Reliability evaluation of simulation models for nearfield groundwater flow and radionuclide transport computation

*; *; *; *

JNC-TJ8400 2000-005, 71 Pages, 2000/05

JNC-TJ8400-2000-005.pdf:4.0MB

In this research, simulations with some parameters which characterize ground water flow and the reliability evaluation for the expansion of the calculation method of groundwater flow were carried out by using the radionuclide transport computations in nearfield heterogeneous porous media. Concretely contents are follows: (1)With the series of calculation method for three-dimensional saturated/unsaturated groundwater flow and one-dimensional radionuclide transport, the computational analyses with the parameters used in JNC report in 2000 was carried out and the influence of the different input flux was evaluated. (2)The examination of the application for the different ways of inverse laplace transformation which is used in one-dimensional radionuclide transport analysis code "MATRICS" was carried out. (3)The examination of the application of multi-element "MATRICS" (m-MATRICS) for radionuclide transport computations in nearfield heterogeneous porous media was carried out. (4)The series of calculation methods from three-dimensional saturated/unsaturated ground water flow simulation code to one-dimensional radionuclide transport simulation code was integrated.

JAEA Reports

Reliability evaluation for radionuclide transport analysis code MATRICS

*; Ijiri, Yuji*; *; *

JNC-TN8400 2000-021, 66 Pages, 2000/04

JNC-TN8400-2000-021.pdf:1.74MB

A reliability evaluation for radionuclide transport analysis code, MATRICS, used in radionuclide transport analysis in the natural barrier system PA in H12 report has been carried out. Sensitivity analysis to radionuclide transport parameter in MATRICS and analytical solution has been performed, and the results of each analysis have been compared. Additionally sensitivity analysis using Talbot Method, Crump method and Hosono method has been carried out, and the results of each inverse Laplace transform method has been compared. The conclusions obtained from the results of the evaluation are summarized as follows, (1)In case of the infinite matrix diffusion distance, an error among the results of each calculation is maximum about 0.4% in the range of Pe number from 1.0 to 100. And, an error among the results of each calculation is maximum about 5.5% in the range of transmissivity from 1.0$$times$$10$$^{-10}$$ to 1.0$$times$$10$$^{-5}$$(m$$^{2}$$/s). (2)In case of the finite matrix diffusion distance (0.03$$sim$$1.0(m)), an error among the results of each calculation is maximum about 0.7% in the range of Pe number from 1.0 to 100. And, an error among the results of each calculation is maximum about 2.4% in the range of transmissivity from 1.0$$times$$10$$^{-10}$$ to 1.0$$times$$10$$^{-5}$$(m$$^{2}$$/s). 3)By comparing Talbot method with other inverse Laplace transform method, Talbot method is confirmed to give similar results with other inverse Laplace transform method in the range of Pe number from 5.0$$times$$10$$^{-1}$$ to 2.0$$times$$10$$^{3}$$, and that of transmissivity below 1.0$$times$$10$$^{-7}$$(m$$^{2}$$/s). Therefore, it is concluded that the reliability of MATRICS are confirmed by conducting sensitivity analysis in the range of Pe number and transmissivity coefficient used in H12 report.

JAEA Reports

None

Federation of Electric Power Companies of Japan*

JNC-TY1400 2000-001, 464 Pages, 2000/03

JNC-TY1400-2000-001.pdf:16.87MB

None

JAEA Reports

Certification of reliability of nuclide migration data

Ueda, Shinzo*; *; *; *

JNC-TJ8400 2000-002, 316 Pages, 2000/02

JNC-TJ8400-2000-002.pdf:14.28MB

Japan Nuclear Cycle Development Institute (JNC) have been setting migration parameters and developing its database for the 2nd Progress Report of HLW Geological Disposal (H12 Report). In this study, experimentswere carried out to certify the reliability of parameters and scenario, and examination was carried out to survey procedures of quality management. The main contents are as follows. (1)Data acquisition for certification of migration parameters. The effect of NH$$_{3}$$ complex of Pd on distribution coefficients (Kd) of Pd on both bentonite and rocks, and the effect of sulfate and carbonate complexes of Am on Kds of Am on bentonite are investigated. Kds of Pd depended on NH$$_{4}^{+}$$ concentration in aqueous. The dependence varied with pH. Effects of sulfate and carbonate complexes on Kds of Am were not remarkable. Apparent diffusivities of Cs in bentonite saturated by saline water were measured. It was confirmed that the apparent diffusivities of Cs in saline water were similar to those in pure water. (2)Evaluation of colloidal effect on nuclide migration. An evaluation of validity of analytical model (Hwang's model) for nuclide migration under existence of colloids and investigation of characterization of colloids in groundwater were carried out. As the results, it was indicated that the Hwang's model was appropriate, and it was found that samplingtechnique influenced concentration and size distribution of colloids. (3)Influence of organic substances on solubility. Solubility of Th was measured under the condition with humic acid and carbonate. It increased roughly in proportion to the concentration of humic acid. And it was remarkably high under the condition with carbonate. It was confirmed that Th solubility data set in H12 report was conservative, even though humic acid existed in groundwater. (4)Use of Mechanistic Models for Safety Assessment. The integrated sorption/diffusion model has been used to calculate K$$_{d}$$, D$$_{a}$$ and D$$_{e}$$ values ...

JAEA Reports

The Development of MESHNOTE Code for Radionuclide Migration in the Near Field

; Makino, Hitoshi; Peter*

JNC-TN8400 99-095, 69 Pages, 1999/12

JNC-TN8400-99-095.pdf:3.05MB

MESHNOTE code was developed to evaluate the engineered barrier system in collaboration with QuantiSci. This code is used to simulate glass dissolution, diffusive transport of nuclides in the buffer material and release to surrounding host rock. MESHNOTE is a one-dimensional finite difference, code, which uses cylindrical co-ordinates for the solution of a radially symmetric diffusion problem. MESHNOTE has the followig characteristics: (1) MESHNOTE can solve for diffusive transport of nuclides through an annulus shaped buffer region while accounting for multiple decay chains, linear and non-linear sorption onto the buffer materials and elemental solubility limits; (2) MESHNOTE can solve for ingrowth of plural daughter nuclides from a singular parent nuclide (branching), and the ingrowth of a singular daughter nuclide from plural parent nuclides (rejoining); (3) MESHNOTE can treat the leaching of nuclide from the vitrified waste and the release of nuclide from buffer to surrounding rock, which are boundary conditions for migration in the buffer, basing on the phenomena; (4) MESHNOTE can treat principal parameters (e.g. solubility and distribution coefficient) relevant to nuclide migration as time and space-dependence parameters; (5) The time stepping scheme in MESHNOTE is controlled by tolerance defined by the user. The time stepping will increase automatically while checking the accuracy of the numerical solution. The conceptual model, the mathematical model and the numerical implementation of the MESHNOTE code are described in this report and the characteristic functions of MESHNOTE are verified by comparing with analytical solutions or simulations produced with other calculation codes.

JAEA Reports

Porosity and Density of Fractured Zone at the Kamaishi Mine

Sato, Haruo

JNC-TN8400 99-061, 9 Pages, 1999/10

JNC-TN8400-99-061.pdf:1.15MB

The porosities and dry densities for rock samples sampled from a fractured zone (fracture type C: composed of intact ganodiorite, altered ganodiorite and fracture fillings) at the Kamaishi mine were obtained by a water saturation (intrusion) method as input parameters for nuclide migration analysis in performance assessment of the geological disposal of high-level radioactive waste. Consequently, the average porosity, 8.6$$pm$$0.43%、 was higher than those of fracture fillings, altered garnodiorite and intact ganodiorite composing fracture type B with a single fracture taken from the Kamaishi mine so far. While, the average dry density, 2.43$$pm$$0.0089 Mg$$cdot$$m$$^{-3}$$, was lower than those of rocks composing the fracture type B. Based on this, it is predicted that radionuclides are the easiest to migrate in the fracture zone.

JAEA Reports

Sorption and Diffusion Behavior of Palladium in Bentonite,Granodiorite and Tuff

; ; Sato, Haruo; Shibata, Masahiro

JNC-TN8400 99-088, 58 Pages, 1999/06

JNC-TN8400-99-088.pdf:2.72MB

Sorption and diffusion behavior of palladium, which has been identified as one of the hazardous radionuclides in performance assessment of HLW disposal, in bentonite, granodiorite and tuff was studied in order to make reliable data set for the performance assessment. Sorption experiments of Pd on bentonite, granodiorite and tuff were conducted as functions of pH, ionic strength and liquid to solid ratio by batch method under aerobic conditions at room temperature. The distribution coefficients (K$$_{d}$$) of Pd on these solids were almost in the range of 10$$^{-1}$$ to 10$$^{2}$$ m$$^{3}$$/kg and were in the order of bentonite $$>$$ granodiorite $$simeq$$ tuff. The sorption trends with change in PH, ionic strength and liquid to solid ratio are very similar between three solids. The K$$_{d}$$ values were the highest at pH5 and decreased with increasing pH between 5 and 11. The effect of ionic strength on K$$_{d}$$ was not found in a range of 10$$^{-2}$$ to 10$$^{-1}$$, but K$$_{d}$$ values increased with increasing liquid to solid ratio. The width of variation in K$$_{d}$$ was one order of magnitude in a liquid to solid ratio of 0.1 to 1 m$$^{3}$$/kg. Sorption behavior of Pd is different from that of divalent metal ions such as Ni and Co etc. and chemical analogy may be inappropriate. The dominant aqueous species of Pd in the expermental conditions studied is estimated to be neutral species, Pd(OH)$$_{2}$$(aq) by the thermodynamic calculations. The K$$_{d}$$ values of Pd on three solids were relatively high and uncharged complexes may be more strongly sorbed. The pH dependency of K$$_{d}$$ values suggests that Pd sorption is most likely to be occurring onto positively charged S-OH$$_{2}$$ type site which are progressively removed (to from SOH and SO$$_{-}$$ sites) at higher pH values. Diffusion behavior of Pd in bentonite was also studied by in-diffusion method as a function of dry density. The D$$_{a}$$ values obtained based on the instantaneous planar source model were in the orders of ...

Oral presentation

Development of safety assessment methodology considering the evolution of geological disposal system, 3; Analysis of radionuclide migration with consideration of spatial and temporal change of migration parameters

Shimada, Taro; Takubo, Kazuya; Takeda, Seiji; Tanaka, Tadao

no journal, , 

In long-term safety assessment of geological disposal system, it is necessary to evaluate the impact on the nuclides migration where groundwater flow and water composition are changed with decreasing a depth of the repository by uplifts and denudation. Therefore, we developed an integrated safety assessment methodology for uplifts and denudation where nuclides migration was evaluated reflecting temporal and spatial changes of parameters of natural and engineered barriers such as distribution coefficient, porosity and groundwater velocity, which were obtained by calculation of groundwater flow, salt water distribution and long-term transition of engineered barriers. The methodology was applied to an assumed disposal site composed of sedimentary rocks with uplift and denudation. Migration parameters of engineered barrier such as coefficient of water permeability and porosity of buffer material were evaluated considering the interaction between overpack and surrounding bentonite clay under the condition of water composition. Migration parameters of the natural barrier such as distribution coefficient were determined by the combination of the geology section and water composition section on the migration pathway from the repository to the outlet of the natural barrier at the depth of 40m from the surface. The migration fluxes of some radionuclides at the outlet of natural barrier were evaluated and then the impacts on nuclides migration by uplifts and denudation were compared.

Oral presentation

Evaluation methodology for influence of splay fault growth on geological disposal system, 2; Analysis of radionuclide migration with consideration of fault growth

Shimada, Taro; Takubo, Kazuya; Takai, Shizuka; Takeda, Seiji; Tanaka, Tadao

no journal, , 

There is a residual uncertainty not able to avoid geological and climate events because some indications of them are difficult to be detected, while direct damage by the events such as active fault is avoided at site selection. Therefore radionuclide migration analysis was carried out considering safety functions of engineered barrier decreased or lost by intersection of fault and temporal and spatial changes of nuclide migration pathway under the assumption that concealed spray fault reaches the disposal system. And we evaluated the affects by inflow of fluid from deep region and of acidic groundwater from the surface along the grown spray fault. Based on the results of groundwater flow analysis, we calculated the nuclides migration fluxes at the outlet of engineered and natural barriers using nuclides migration parameters such as migration pathway, its length and groundwater velocity and sorption distribution coefficients estimated by combination of groundwater composition and geology. And important factors to affect the fluxes were extracted.

Oral presentation

Nuclide migration analysis model

Mihara, Morihiro

no journal, , 

The nuclide migration analysis model is an important model to evaluate the dissolution and transport of nuclides in groundwater. This model consists of diffusion and advection/dispersion of nuclides and has been developed in consideration of decay chains of nuclides, sorption to the solid phase, and dissolution / precipitation. This slides introduces the nuclide migration analysis models and analysis examples used in the 2nd progress report and the TRU-2 report.

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