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Iodide retention by modified kaolinite in the context of safe disposal of high level nuclear waste

Sadasivam, Siva and Rao, Sudhakar M 2012. Iodide retention by modified kaolinite in the context of safe disposal of high level nuclear waste. Journal of Hazardous, Toxic, and Radioactive Waste 16 (3) , pp. 192-200. 10.1061/(ASCE)HZ.2153-5515.0000121

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Abstract

Bentonite clay is identified as potential buffer in deep geological repositories (DGR) that store high level radioactive wastes (HLW) as the expansive clay satisfies the expected mechanical and physicochemical functions of the buffer material. In the deep geological disposal of HLW, iodine-129 is one of the significant nuclides, attributable to its long half-life (half life=1.7×107  years). However, the negative charge on the basal surface of bentonite particles precludes retention of iodide anions. To render the bentonite effective in retaining hazardous iodide species in DGR, improvement of the anion retention capacity of bentonite becomes imperative. The iodide retention capacity of bentonite is improved by admixing 10 and 20% Ag-kaolinite (Ag-K) with bentonite (B) on a dry mass basis. The present study produced Ag-kaolinite by heating silver nitrate-kaolinite mixes at 400°C. Marginal release of iodide retained by Ag-kaolinite occurred under extreme acidic (pH=2.5) and alkaline (pH=12.5) conditions. The swell pressure and iodide retention results of the B-Ag-K specimens bring out that mixing Ag-K with bentonite does not chemically modify the expansive clay; the mixing is physical in nature and Ag-K presence only contributes to iodide retention of the admixture.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Subjects: Q Science > QE Geology
T Technology > TA Engineering (General). Civil engineering (General)
Uncontrolled Keywords: Bentonite, Iodide, Radionuclides, Repository, Retention
Additional Information: Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/2153-5493/ (accessed 25/02/2014)
Publisher: American Society of Civil Engineers
ISSN: 2153-5493
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 04:57
URI: http://orca.cf.ac.uk/id/eprint/46730

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