Modeling the Radionuclide Migration Experiments at Grimsel. What Have We Learned?

1997 ◽  
Vol 506 ◽  
Author(s):  
W. Heer ◽  
P.A. Smith
Keyword(s):  
Performance Assessment ◽  
Test Site ◽  
Radionuclide Migration ◽  
Consistent Description ◽  
Grimsel Test Site ◽  
Tracer Migration ◽  
High Degree

ABSTRACTFor several years, tracer migration experiments at Nagra's Grimsel Test Site have been performed with an exceptionally high degree of precision. A summary of the main findings obtained by modelling these experiments is presented, addressing, in particular the influence of sorption. A consistent description of tracer behaviour is achieved, giving confidence when applying broadly similar methodologies and models in geosphere performance assessment.

Results of the colloid and radionuclide retention experiment (CRR) at the Grimsel Test Site (GTS), Switzerland – impact of reaction kinetics and speciation on radionuclide migration

2004 ◽  
Vol 92 (9-11) ◽  
Author(s):  
Horst Geckeis ◽  
Thorsten Schäfer ◽  
W. Hauser ◽  
Thomas Rabung ◽  
T. Missana ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Test Site ◽  
Radionuclide Migration ◽  
Migration Behaviour ◽  
Grimsel Test Site

SummaryThe influence of smectite colloids on the migration behaviour of U(VI), Th(IV), Pu(IV), Am(III), Np(V), Sr(II) and Cs(I) is investigated within the Colloid and Radionuclide Retardation experiment (CRR). Two

The Assessment of Radionuclide Retardation in Fractured Crystalline Rocks

1997 ◽  
Vol 506 ◽  
Author(s):  
W. Russell Alexander ◽  
Kunio Ota ◽  
Bernhard Frieg ◽  
Ian G. Mckinley
Keyword(s):  
Test Site ◽  
Breakthrough Curves ◽  
Swiss Alps ◽  
Radionuclide Migration ◽  
Sorption Data ◽  
Kd Values ◽  
Long Term Experiment ◽  
Fractured Crystalline Rocks ◽  
Tracer Migration

ABSTRACTThe joint Nagra/PNC Radionuclide Migration Programme has been running for over ten years in Nagra‘s Grimsel Test Site in the central Swiss Alps. The programme is specifically aimed at the further development of conceptual models of radionuclide transport in the geosphere, rigorously testing the applicability of current transport codes to quantify radionuclide migration in situ and assessing how successfully laboratory sorption data (specifically, Kd values) may be extrapolated to in situ conditions to predict radionuclide retardation in the geosphere [1]. A large series of field tracer migration experiments was carried out in a hydrologically well characterised water-bearing, complex fracture (or shear zone), increasing in complexity from simple, nonsorbing fluoresceine (a fluorescent dye), 3H, 3,4He, 82Br and 123I through weakly sorbing 22.24Na,85Sr and 86Rb to a final, long-term experiment with moderately sorbing 134,137Cs. The radionuclides were injected into a dipole flow field where the flowpath length, dipole width or shape and groundwater flow velocity were all varied. After a considerable learning period, generally good fits could be obtained between transport code predictions and subsequent field tracer breakthrough curves, suggesting that the transport codes tested were a reasonable representation of in situ conditions.

Grimsel 2000 – Status of International Projects at the Grimsel Test Site (GTS)

2000 ◽  
Vol 663 ◽  
Author(s):  
W. Kickmaier ◽  
W. R. Alexander ◽  
S. Vomvoris ◽  
I.G. McKinley
Keyword(s):  
Performance Assessment ◽  
Test Site ◽  
Swiss Alps ◽  
Geological Environment ◽  
Grimsel Test Site ◽  
Fundamental Understanding ◽  
International Projects ◽  
Integrated Performance ◽  
Future Work ◽  
Integrated Performance Assessment

ABSTRACTDuring 17 years of cooperation, the Grimsel underground test site in the Swiss Alps has become established as a major center for study of the deep geological environment. The present Phase V of operation involves collaboration of 15 organizations from 9 countries.The 7 major projects currently running can be divided into 3 areas:- Confirmation of fundamental understanding and testing of models of processes identified to be significant in integrated performance assessment- Demonstration and optimization of site characterization technology- Demonstration of the technology for constructing and operating a deep repository in an efficient and quality assured manner.This sub-division of projects is somewhat simplistic as, wherever possible, large, long- running experiments are designed to achieve a number of goals. The paper will provide a summary of some projects running at Grimsel, an overview of the rationale behind the experimental concepts and a perspective on possible future work.

The Excavation Project in the Grimsel Test Site: In Situ High-Resolution Gamma and Alpha Spectrometry of 60Co, 75Se, 113Sn, 152Eu, 235U, and 237Np/233Pa

1997 ◽  
Vol 506 ◽  
Author(s):  
J. Eikenberg ◽  
M. Ruethi ◽  
W.R. Alexander ◽  
B. Frieg ◽  
T. Fierz
Keyword(s):  
High Resolution ◽  
Shear Zone ◽  
Test Site ◽  
Breakthrough Curves ◽  
Laboratory Measurements ◽  
Radionuclide Migration ◽  
Grimsel Test Site ◽  
On Line ◽  
Comprehensive Study

ABSTRACTFull excavation of a water-conducting shear zone used for radionuclide migration experiments is part of a comprehensive study to physically determine the sites of in-situ radionuclide retardation. Prior to the excavation, multi-tracer solutions containing strongly sorbing y- and αemitting nuclides were injected into the shear zone and the water extracted was analyzed on-line using in situ, high-resolution y-spectrometry. In addition, water samples were collected to compare quantitatively the on-line data with subsequent laboratory measurements α- and γ- spectrometry) and also to analyze samples with activities below the detection limits of the in-situ analysis. The breakthrough curves indicate that Se had passed through the fracture with a velocity comparable to a conservatively behaving dye (uranine), but very strong retardation of Co. Eu and Sn was observed. The recoveries of these nuclides were found to be in the order of only a few percent when the dipole flow-field was interrupted about one month after radionuclide injection and the fracture was sealed off for excavation. Significant retardation was also obtained for the oxemitters U, Np and Pa. Almost identical breakthrough curves for these actinides were measured, suggesting a similar spatial distribution in the fracture at any given time.

Modeling of an in-situ diffusion experiment in granite at the Grimsel Test Site

2014 ◽  
Vol 1665 ◽  
pp. 85-91 ◽  
Author(s):  
Josep M. Soler ◽  
Jiri Landa ◽  
Vaclava Havlova ◽  
Yukio Tachi ◽  
Takanori Ebina ◽  
...  
Keyword(s):  
Effective Diffusion ◽  
Test Site ◽  
Diffusion Experiment ◽  
Bulk Rock ◽  
Disturbed Zone ◽  
Mean Grain Size ◽  
Grimsel Test Site ◽  
In Situ Diffusion

ABSTRACTMatrix diffusion is a key process for radionuclide retention in crystalline rocks. Within the LTD project (Long-Term Diffusion), an in-situ diffusion experiment in unaltered non-fractured granite was performed at the Grimsel Test Site (www.grimsel.com, Switzerland). The tracers included 3H as HTO, 22Na+, 134Cs+ and 131I- with stable I- as carrier.The dataset (except for 131I- because of complete decay) was analyzed with different diffusion-sorption models by different teams (NAGRA / IDAEA-CSIC, UJV-Rez, JAEA, Univ. Poitiers) using different codes, with the goal of obtaining effective diffusion coefficients (De) and porosity (ϕ) or rock capacity (α) values. A Borehole Disturbed Zone (BDZ), which was observed in the rock profile data for 22Na+ and 134Cs+, had to be taken into account to fit the experimental observations. The extension of the BDZ (1-2 mm) was about the same magnitude as the mean grain size of the quartz and feldspar grains.De and α values for the different tracers in the BDZ are larger than the respective values in the bulk rock. Capacity factors in the bulk rock are largest for Cs+ (strong sorption) and smallest for 3H (no sorption). However, 3H seems to display large α values in the BDZ. This phenomenon will be investigated in more detail in a second test starting in 2013.

Studies on radionuclide transport behaviour–The next generation of in-situ experiments at the Grimsel Test Site

2009 ◽  
Vol 1193 ◽  
Author(s):  
Andrew James Martin ◽  
Ingo Blechschmidt
Keyword(s):  
Shear Zone ◽  
Diffusion Processes ◽  
Test Site ◽  
Core Material ◽  
Laboratory Studies ◽  
Grimsel Test Site ◽  
And Migration ◽  
Colloid Formation

AbstractTwo recent ongoing major projects at the Grimsel Test Site (GTS) (www.grimsel.com) that were initiated to simulate the long-term behaviour of radionuclides in the repository near-field and the surrounding host rock are presented: the Colloid Formation and Migration (CFM) project, which focuses on colloid generation and migration from a bentonite source doped with radionuclides and the Long-Term Diffusion (LTD) project, which aims at in-situ verification and understanding of the processes that control the long-term diffusion of repository-relevant radionuclides. So far, the CFM project has principally involved: development and implementation of a state-of-the-art sealing concept to control hydraulic gradients in a shear zone to imitate repository-relevant conditions; extensive laboratory studies to examine bentonite erosion and colloid formation in a shear zone; and, development of models to estimate colloid formation and migration. The next stage will be to assess the behavior of bentonite colloids generated from a radionuclide spiked bentonite source-term emplaced into the controlled flow field of the shear zone. This will be coupled with further extensive laboratory studies in order to refine and evaluate the colloid models currently used in performance assessments. The LTD project consists of: a monopole diffusion experiment where weakly sorbing and non-sorbing radionuclides (3H, 22Na, 131I, 134Cs) have been circulating and diffusing into undisturbed rock matrix since June 2007; experiments to characterise pore space geometry, including determination of in-situ porosity with 14C doped MMA resin for comparison with laboratory derived data; a study of natural tracers to elucidate evidence of long-term diffusion processes; and, an investigation of the in-situ matrix diffusion paths in core material from earlier GTS experiments. Future experiments will focus on diffusion processes starting from a water-conducting feature under realistic boundary conditions.

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