Modelling of the LTDE-SD radionuclide diffusion experiment in crystalline rock at the sp Hard Rock Laboratory (Sweden)

Soler, J. M.*; Meng, S.*; Moreno, L.*; Neretnieks, I.*; Liu, L.*; Keklinen, P.*; Hokr, M.*; ha, J.*; Vetenk, A.*; Reimitz, D.*; et al.

Geologica Acta, 20(7), 32 Pages, 2022/07

https://doi.org/10.1344/GeologicaActa2022.20.7

Task 9B of the SKB Task Force on Modelling of Groundwater Flow and Transport of Solutes in fractured rock focused on the modelling of experimental results from the LTDE-SD in situ tracer test performed at the sp Hard Rock Laboratory in Sweden. Ten different modelling teams provided results for this exercise, using different concepts and codes. Three main types of modelling approaches were used: (1) analytical solutions to the transport-retention equations, (2) continuum-porous-medium numerical models, and (3) microstructure-based models accounting for small-scale heterogeneity (i.e. mineral grains and microfracture distributions). The modelling by the different teams allowed the comparison of many different model concepts, especially in terms of potential zonations of rock properties (porosity, diffusion, sorption), such as the presence of a disturbed zone at the rock and fracture surface, the potential effects of micro- and cm-scale fractures.

Experimental study on modeling of Pu sorption onto quartz

Hemmi, Ko; Walker, A.*; Yamaguchi, Tetsuji

Radiochimica Acta, 109(7), p.539 - 546, 2021/07

https://doi.org/10.1515/ract-2020-0068

Plutonium(IV) sorption onto quartz in carbonate solutions was systematically investigated under anaerobic conditions to analyze the sorption behaviors of Pu(IV) with a non-electrostatic model (NEM). Pu(IV) sorption data was obtained from batch sorption experiments as a function of pH and carbonate concentration. The Pu(IV) sorption onto quartz showed similar tendencies to Th(IV), which is considered to be chemically analogous as a tetravalent actinoid. The distribution coefficient, d, of Pu(IV) onto quartz showed inverse proportionality to the square of the total carbonate concentration under the investigated pH conditions of 8 to 11. The modeling study, however, revealed a Th(IV) sorption model, which is SOTh(OH) and SOThOH(CO), could not be applied to simulate the Pu(IV) sorption onto quartz. It was inferred that the electrostatic repulsion between negatively charged ligands limited the formation of SOM(OH) and SOMOH(CO) for Pu(IV) with smaller ionic radii than Th(IV). The Pu(IV) sorption model was developed as SOPu(OH) and SOPu(OH). In addition, data of Pu(IV) sorption onto muscovite was obtained in order to be compared with data for quartz.

Consideration on modeling of Nb sorption onto clay minerals

Yamaguchi, Tetsuji; Ohira, Saki; Hemmi, Ko; Barr, L.; Shimada, Asako; Maeda, Toshikatsu; Iida, Yoshihisa

Radiochimica Acta, 108(11), p.873 - 877, 2020/11

https://doi.org/10.1515/ract-2020-0006

Evaluation and modelling report of Task 9A based on comparisons and analyses of predictive modelling results for the REPRO WPDE experiments; Task 9 of SKB Task Force GWFTS - Increasing the realism in solute transport modelling based on the field experiments REPRO and LTDE-SD

Soler, J. M.*; Neretnieks, I.*; Moreno, L.*; Liu, L.*; Meng, S.*; Svensson, U.*; Trinchero, P.*; Iraola, A.*; Ebrahimi, H.*; Molinero, J.*; et al.

SKB R-17-10, 153 Pages, 2019/01

The SKB Task Force is an international forum on modeling of groundwater flow and solute transport in fractured rock. The WPDE experiments are matrix diffusion experiments in gneiss performed at the ONKALO underground facility in Finland. Synthetic groundwater containing several conservative and sorbing tracers was injected along a borehole interval. The objective of Task 9A was the predictive modeling of the tracer breakthrough curves from the WPDE experiments. Several teams, using different modelling approaches, participated in this exercise. An important conclusion from this exercise is that the modeling results were very sensitive to the magnitude of dispersion in the borehole opening, which is related to the flow of water. Focusing on the tails of the breakthrough curves, which are more directly related to matrix diffusion and sorption, the results from the different teams were more comparable. The modeling results have also been finally compared to the measured breakthroughs.

Evaluation of effective dose coefficient with variation of absorption fraction in gastrointestinal system for ingestion of radiocesium

Pratama, M. A.; Takahara, Shogo; Hato, Shinji*

Hoken Butsuri, 52(3), p.200 - 209, 2017/09

https://doi.org/10.5453/jhps.52.200

The purpose of this study is to identify the significance of the change in the intestinal absorption rate values the ( value) to the change of dose coefficient as well as to provide a list of dose coefficients which each of the value corresponds to a specific intestinal absorption rate and age groups. In the range of 0-1, 10 different values of for 1 year, 5 years old, and adult group were chosen and used in a separate calculation by using, a biokinetic compartment model, DCAL. It was found that the lower values of intestinal absorption rate lead to a significant decrease of the committed effective coefficient for adult. Oppositely for children, the decrease of committed effective coefficient was not as significant. This study also suggests that the significance of dose coefficient change due to the variation of substantially depends on the biological half-life of the radionuclide and the mass of organs and tissues in human body.

Clay-based modeling approach to diffusion and sorption in the argillaceous rock from the Horonobe URL; Application to Ni(II), Am(III), and Se(IV)

Tachi, Yukio; Suyama, Tadahiro; Yotsuji, Kenji; Ishii, Yasuo; Takahashi, Hiroaki*

CMS Workshop Lectures, Vol.21, p.241 - 250, 2016/00

https://www.clays.org/other-cms-publications-wrksh21/

Sorption and diffusion of radionuclides in argillaceous rocks are key processes in the safe geological disposal. The diffusion and sorption behavior of Ni(II), Am(III) and Se(IV) in mudstone from the Horonobe URL were investigated by experimental and modeling approaches. Effective diffusivities obtained by the through-diffusion experiments were in the sequence of Cs, Ni, HTO, I, Se(SeO), Am(Am(CO)) by comparison with the previous study. The distribution coefficient values were consistent with those obtained by batch sorption tests. These results were interpreted by the clay-based modeling approach coupling the thermodynamic sorption model assuming key contributions of clays (smectite and illite) and the diffusion model assuming the electrical double layer theory and the simplified pore model with size distribution. This clay-based model could provide reasonable account of observed trends and could be basically applicable for various radionuclides.

JENDL photonuclear data file

Kishida, Norio*; Murata, Toru*; Asami, Tetsuo*; Kosako, Kazuaki*; Maki, Koichi*; Harada, Hideo*; Lee, Y.*; Chang, J.*; Chiba, Satoshi; Fukahori, Tokio

AIP Conference Proceedings 769, p.199 - 202, 2005/05

https://doi.org/10.1063/1.1944989

Nuclear data for photonuclear reactions are required in the field of shielding design of high-energy electron accelerators and high-energy -ray therapy. The JENDL Photonuclear Data File was prepared by a working group on nuclear data evaluations for photonuclear reactions in Japanese Nuclear Data Committee. From a survey of many literatures, it is difficult to construct the photonuclear data file by using only measured data, since there are not sufficient experimental data. We were therefore evaluating with theoretical calculations based on statistical nuclear reaction models. The photonuclear cross sections that are to be contained in the file are as follows: photoabsorption cross sections, yield cross sections and DDX for neutrons, protons, deuterons, tritons, He-particles and alpha-particles, and isotope production cross sections. For the actinide nuclides, photofission cross sections are also included. The maximum energy of incident photons is 140 MeV and stored are the photonuclear data for 68 nuclides from H to Np.

Adsorption mechanisms and models of Sr, Np, Pu and Am in loess media (Joint research)

Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Matsumoto, Junko; Ogawa, Hiromichi; Li, S.*; Wang, Z.*; Wang, J.*; Guo, Z.*; Zhao, Y.*

JAERI-Research 2002-034, 20 Pages, 2002/12

JAERI-Research-2002-034.pdf:1.1MB

Adsorption mechanisms and models of Sr(II), Np(V), Pu(IV) and Am(III) on the loess were investigated from their adsorption and desorption properties. The distribution coefficient of Sr and Np was 2 - 3 orders of magnitude smaller than that of Pu and Am. The adsorption of Sr and Np was mainly controlled by the ion exchange reaction. On the other hand, the adsorption of Pu and Am was mostly controlled by the selective chemical reactions with Fe and Mn oxyhydroxide/oxide and humic substances. On the basis of the experimental results, several types of adsorption models of the radionuclides, considering elemental concentrations, adsorption mechanisms and kinetics, were proposed for setting up the analytical systems of radionuclide migration in the loess media.

Dynamic behaviors of fragments ejected from the surface of carbon materials by laser ablation

Yoda, Osamu; Miyashita, Atsumi; ;

JAERI-M 92-173, 27 Pages, 1992/10

JAERI-M-92-173.pdf:1.22MB

no abstracts in English

Sorption behaviour of lead onto montmorillonite in the presence of carbonate

Sugiura, Yuki; Ishidera, Takamitsu; Suyama, Tadahiro*; Okazaki, Mitsuhiro*; Hamamoto, Takafumi*; Ishida, Keisuke*; Tachi, Yukio

no journal, ,