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A physico-chemical characterisation technique for determining the pore-water chemistry in argillaceous rocks

Technical Report:

Abstract

A prerequisite for carrying out credible sorption studies is the definition of an aqueous phase composition which is in equilibrium with the solid phase. Experimental methods and data analysis procedures are described which enable an equilibrium water composition to be produced for argillaceous rocks which is not dependent on liquid to solid (L:S) ratios. Since a Valanginian marl formation is under consideration by Nagra as a potential rock for the disposal of low and short-lived medium level radioactive waste in Switzerland, samples of this material were chosen for this investigation. Aqueous phase and nickel ethylenediamine extraction experiments were carried out at different L:S ratios under controlled atmosphere conditions (P{sub CO{sub 2}}=10{sup -2} bar, O{sub 2}{<=} 5 ppm ). The results from these tests and petrographical examinations were combined to define the system in terms of the physico-chemical characteristics of the clay mineral component (CEC and cation occupancies) and the identities of highly soluble and solubility limited phases in the marl. The geochemical code PHREEQE was used in conjunction with the Gapon equations to calculate the pore water composition. This work clearly showed that pore water chemistries obtained from aqueous extracts alone may lead to an arbitrary water chemistry in argillaceous  More>>
Authors:
Baeyens, B; Bradbury, M H [1] 
  1. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Publication Date:
Sep 01, 1991
Product Type:
Technical Report
Report Number:
PSI-103
Reference Number:
SCA: 540250; 052002; PA: AIX-23:010983; SN: 92000637721
Resource Relation:
Other Information: PBD: Sep 1991
Subject:
54 ENVIRONMENTAL SCIENCES; 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; CLAYS; POROSITY; SWITZERLAND; RADIOACTIVE WASTE DISPOSAL; UNDERGROUND DISPOSAL; SITE CHARACTERIZATION; CARBON DIOXIDE; CATIONS; CHEMISORPTION; EXPERIMENTAL DATA; ION EXCHANGE; MATHEMATICAL MODELS; NICKEL COMPLEXES; P CODES; THEORETICAL DATA; WATER CHEMISTRY; 540250; 052002; SITE RESOURCE AND USE STUDIES; WASTE DISPOSAL AND STORAGE
OSTI ID:
10111873
Research Organizations:
Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Country of Origin:
Switzerland
Language:
English
Other Identifying Numbers:
Other: ON: DE92613488; TRN: CH9100667010983
Availability:
OSTI; NTIS (US Sales Only); INIS
Submitting Site:
CHN
Size:
67 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Baeyens, B, and Bradbury, M H. A physico-chemical characterisation technique for determining the pore-water chemistry in argillaceous rocks. Switzerland: N. p., 1991. Web.
Baeyens, B, & Bradbury, M H. A physico-chemical characterisation technique for determining the pore-water chemistry in argillaceous rocks. Switzerland.
Baeyens, B, and Bradbury, M H. 1991. "A physico-chemical characterisation technique for determining the pore-water chemistry in argillaceous rocks." Switzerland.
@misc{etde_10111873,
title = {A physico-chemical characterisation technique for determining the pore-water chemistry in argillaceous rocks}
author = {Baeyens, B, and Bradbury, M H}
abstractNote = {A prerequisite for carrying out credible sorption studies is the definition of an aqueous phase composition which is in equilibrium with the solid phase. Experimental methods and data analysis procedures are described which enable an equilibrium water composition to be produced for argillaceous rocks which is not dependent on liquid to solid (L:S) ratios. Since a Valanginian marl formation is under consideration by Nagra as a potential rock for the disposal of low and short-lived medium level radioactive waste in Switzerland, samples of this material were chosen for this investigation. Aqueous phase and nickel ethylenediamine extraction experiments were carried out at different L:S ratios under controlled atmosphere conditions (P{sub CO{sub 2}}=10{sup -2} bar, O{sub 2}{<=} 5 ppm ). The results from these tests and petrographical examinations were combined to define the system in terms of the physico-chemical characteristics of the clay mineral component (CEC and cation occupancies) and the identities of highly soluble and solubility limited phases in the marl. The geochemical code PHREEQE was used in conjunction with the Gapon equations to calculate the pore water composition. This work clearly showed that pore water chemistries obtained from aqueous extracts alone may lead to an arbitrary water chemistry in argillaceous rock systems, particularly with respect to ionic composition and ionic strength, which may have important consequences for radionuclide speciation and sorption studies. (author) 11 figs., 12 tabs., 25 refs.}
place = {Switzerland}
year = {1991}
month = {Sep}
}