Lime mortar-compacted bentonite–magnetite interfaces: An experimental study focused on the understanding of the EBS long-term performance for high-level nuclear waste isolation DGR concept

2016 ◽  
Vol 124-125 ◽  
pp. 79-93 ◽  
Author(s):  
Jaime Cuevas ◽  
Ana Isabel Ruiz ◽  
Raúl Fernández ◽  
Elena Torres ◽  
Alicia Escribano ◽  
...  
1990 ◽  
Vol 212 ◽  
Author(s):  
D. E. Grandstaff ◽  
V. J. Grassi ◽  
A. C. Lee ◽  
G. C. Ulmer

ABSTRACTSystematic differences in pH, cation/proton ion activity ratios, and redox have been observed between solutions produced in rock-water hydrothermal experiments with tuff, granite, and basalt. Stable pH values in tuff-water experiments may be as much as 1.5 pH units more acidic than basalt-water experiments at the same temperature and ionic strength. Redox (log fO2) values in 300°C tuff experiments are 4–7 orders of magnitude more oxidizing than basalt experiments and ca. 4 log units more oxidizing than the magnetite-hematite buffer. Such fluid differences could significantly affect the performance of a high-level nuclear waste repository and should be considered in repository design and siting.


2016 ◽  
Vol 80 (5) ◽  
pp. 765-780 ◽  
Author(s):  
P. Sengupta ◽  
J. Sanwal ◽  
N. L. Dudwadkar ◽  
S. C. Tripathi ◽  
P. M. Gandhi

AbstractStalagmites and stalactites, as observed within natural caves, may develop inside geological repositories during constructional and post-operational periods. It is therefore important to understand actinide sorption within such materials. Towards this, experimental studies were carried out with 233U, 238Np (VI), 238Np (IV), 239Pu and 241Am radiotracers using natural speleothem samples collected from the Dharamjali cave of the Kumaon Lesser Himalayas, India. Petrological/mineralogical studies showed that natural speleothems have three general domains: (1) columnar calcite; (2) microcrystalline calcite; and (3) botryoidal aragonite – each with ferruginous materials. Results showed that all domains of speleothems can take up >99% actinides, irrespective of valence state and pH (1–6 range) of the solution. However, distribution coefficients were found to be at a maximum in aragonite for most of the actinides. Such data are very important for long-term performance and safety assessments of the deep geological repositories planned for the disposal of high-level nuclear wastes.


2019 ◽  
Vol 9 (12) ◽  
pp. 2437 ◽  
Author(s):  
Sebastian Wegel ◽  
Victoria Czempinski ◽  
Pao-Yu Oei ◽  
Ben Wealer

The nuclear industry in the United States of America has accumulated about 70,000 metric tons of high-level nuclear waste over the past decades; at present, this waste is temporarily stored close to the nuclear power plants. The industry and the Department of Energy are now facing two related challenges: (i) will a permanent geological repository, e.g., Yucca Mountain, become available in the future, and if yes, when?; (ii) should the high-level waste be transported to interim storage facilities in the meantime, which may be safer and more cost economic? This paper presents a mathematical transportation model that evaluates the economic challenges and costs associated with different scenarios regarding the opening of a long-term geological repository. The model results suggest that any further delay in opening a long-term storage increases cost and consolidated interim storage facilities should be built now. We show that Yucca Mountain’s capacity is insufficient and additional storage is necessary. A sensitivity analysis for the reprocessing of high-level waste finds this uneconomic in all cases. This paper thus emphasizes the urgency of dealing with the high-level nuclear waste and informs the debate between the nuclear industry and policymakers on the basis of objective data and quantitative analysis.


2006 ◽  
Vol 932 ◽  
Author(s):  
William H Bowyer

ABSTRACTThe Swedish programme for disposal of high level nuclear waste includes the development of a container which comprises a cast iron load bearing canister contained in a 50 mm thick copper corrosionshield.The temperature of the outside of the canister is likely be up to 100°C, and repository processes may lead to long term loads of up to 50MPa. Creep of the copper is therefore an issue. SKB (The Swedish Nuclear Fuel and Waste Management Co.) have been conducted tests on three materials, OF copper containing 10ppm sulphur (OF1), OF copper containing 6ppm sulphur (OF2) and OF copper containing 6ppm sulphur and 50ppm phosphorus (OFP). In order to improve confidence in extrapolation of test results to practical temperatures and stresses, it is desirable to support the extrapolation procedures with a physical model.Life predictions made using the Frost and Ashby model [5] together with a simplification of the Cocksand Ashby model [6] provide good agreement with published experimental data for OF2 and OFPmaterials. Extrapolation of this data using the model leads to life predictions of 12,000 years for the OF2material and 120,000 years for OFP material. The prediction for OFP depends on an assumption that an observed strengthening mechanism conferred by phosphorus at high stresses and temperatures, is equally as effective under repository conditions.OF1 material fails after a relatively short life and by a different mechanism to OF2 and OFP. The changein mechanism may be explained, using the model [6], for cases where segregating species reduce surface energy of grain boundary voids. It is suggested that in this case the segregating species is sulphur.


1993 ◽  
Vol 333 ◽  
Author(s):  
R. A. Van Konynenburg

ABSTRACTThe best possibility for gaining an understanding of the likely future behavior of a high level nuclear waste disposal system is use of the scientific method. However, the scientific approach has inherent limitations when it comes to making long-term predictions with confidence. This paper examines these limiting factors as well as the criteria for admissibility of scientific evidence in the legal arena, and concludes that the prospects are doubtful for successful licensing of a potential repository under the regulations that were binding until recently. Suggestions are made for remedying this situation.


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