Corrosion Behavior of Simulated LLW Glass in Deionized Water

2009 ◽  
Vol 1193 ◽  
Author(s):  
Toshikatsu Maeda ◽  
Tetsuji Yamaguchi ◽  
Katsutoshi Hotta ◽  
Tsuyoshi Mizuno ◽  
Tsunetaka Banba
Keyword(s):  
Radioactive Waste ◽  
Volume Ratio ◽  
Deionized Water ◽  
Water Volume ◽  
Dissolution Mechanism ◽  
Chemical Compositions ◽  
High Concentration ◽  
Geological Repository ◽  
One Year ◽  
High Level

AbstractStatic leach tests were conducted for simulated low-level radioactive waste (LLW) glass in deionized water at 90 °C for up to one year to investigate the dissolution mechanism of LLW glass. Widely studied leaching behavior of high-level radioactive waste (HLW) glass is referred in discussing the dissolution mechanism. LLW glass is characterized by higher sodium (Na) and aluminum (Al) contents than HLW glass, about twice as high as R7T7, with its SiO2 content close to HLW glass. Powdered simulated LLW glass of three different chemical compositions was tested with the glass-surface-to-water-volume ratio of 2,000 m−1. The release rates of boron (B), widely used as an indicator of dissolution for HLW glass, decreased with time during leaching, as commonly observed in similar tests for HLW glass. The pH of the leachate was stable around 11.3 - 11.6, which is higher than those in similar tests for HLW glass by one pH unit or more. The concentrations of Al in the leachates were higher compared to data for HLW glass by two orders of magnitude. The high concentration seems to be caused by higher pH. In the leachate condition of the present tests, a zeolitic mineral (analcime) is thermodynamically more stable than amorphous silica (SiO2(am)) which is known to control the concentration of dissolved silica (Si) with respect to HLW glass. The present results imply that dissolution of the LLW glass is accompanied with formation of analcime under virtually closed systems such as geological repository where the groundwater flow rate is quite low.

Treatment of Refinery Wastewater with Isolated Biological Aerated Filters: A Pilot-Scale Study

2012 ◽  
Vol 610-613 ◽  
pp. 2332-2341
Author(s):  
Jian Guang Huang ◽  
Li Zhong ◽  
Wen Yu Xie
Keyword(s):  
Waste Water ◽  
Waste Water Treatment ◽  
Oxygen Demand ◽  
Volume Ratio ◽  
Pilot Scale ◽  
Mean Value ◽  
Operating Conditions ◽  
Water Volume ◽  
High Concentration ◽  
Set Up

A pilot scale biochemical treatment system containing three isolated biological aerated filters, one oil-separation pool and one secondary sedimentation tank was set up and used for high concentration organic waste water treatment. Effect of different operating conditions on Chemical Oxygen Demand (CODCr), sulphides, hydroxybenzene and oil degradation was investigated. And the ways of sulphides removal were also explored. While CODCr, the concentrations of sulphides, hydroxybenzene and oil in the waste water are no more than 1500 mg/L, 800 mg/L, 15 mg/L and 150mg/L, respectively, the system can run stably and the total removal of these pollutants is 88.8%, 98.8%, 96.8% and 91.0% accordingly though hydraulic retention time (HRT) varies from 7.95 hr to 15.90 hr and the air/water volume ratio (AWVR) varies from 12 to 8. Most of the sulphides are removed by Biodegradation with Isolated Biological Aerated Filters. Most of the pollutants are removed in the 1st BAF and about 96.5% by mean value of sulphides transforme into elemental sulfur and only about 2.7% by mean value of sulphides transforme into sulphates.

Repository Site Characterization: Comparing International Experience

2009 ◽  
Author(s):  
Martin Goldsworthy ◽  
Till Popp ◽  
Knut Seidel ◽  
Johannes Bruns
Keyword(s):  
Radioactive Waste ◽  
Selection Process ◽  
International Experience ◽  
Geological Repository ◽  
Clay Cover ◽  
Under Construction ◽  
High Level ◽  
A Site ◽  
Hlw Repository ◽  
The Ideal

An important part of the work described here was a study of existing international experience in investigating deep geological repository sites. The objective of this study was to derive a basis for planning the content and extent of investigations which might be carried out in Germany in the future. Such investigations would be required in the course of a site selection process for a repository for HLW (high level radioactive waste). For this purpose information on suitable sites was gathered, mainly from literature sources. Suitable in this context meant two things. Firstly, the investigated site should be in rock similar to four being considered in Germany (salt, clay, crystalline and other hard rock under a clay cover). Secondly, the investigations carried out could reasonably be considered as being intended to lead to the use of the site as a repository. The investigation processes were presented, analysed and compared. The comparison was based on the quality and the intensity of the methods employed to obtain the information necessary for deciding between candidate repository sites in terms of safety and the feasibility of construction. In the final stage of the work the analysis and presentation method developed for the international sites was applied to the investigations already carried out at three German sites (Gorleben — a prospective HLW repository, Morsleben — an existing but now not operational repository for radioactive waste and Konrad — a repository currently under construction). The reported investigatory work was compared with the ideal investigations developed on the basis of the existing international experience.

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