Effective thermal conductivity of compact bentonite as a buffer material for high level radioactive waste

1995 ◽  
Vol 27/28 (6) ◽  
pp. 653-663 ◽  
Author(s):  
Hiroshi Kiyohashi ◽  
Katunori Banno
Keyword(s):  
Thermal Conductivity ◽  
Radioactive Waste ◽  
Effective Thermal Conductivity ◽  
High Level Radioactive Waste ◽  
Compact Bentonite ◽  
Buffer Material ◽  
High Level

scholarly journals Thermal Conductivity of Compacted GO-GMZ Bentonite Used as Buffer Material for a High-Level Radioactive Waste Repository

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yong-Gui Chen ◽  
Xue-Min Liu ◽  
Xiang Mu ◽  
Wei-Min Ye ◽  
Yu-Jun Cui ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Radioactive Waste ◽  
Water Content ◽  
Radioactive Waste Disposal ◽  
Dry Density ◽  
Gmz Bentonite ◽  
High Level Radioactive Waste ◽  
Buffer Material ◽  
High Level ◽  
Crucial Parameter

In China, Gaomiaozi (GMZ) bentonite serves as a feasible buffer material in the high-level radioactive waste (HLW) repository, while its thermal conductivity is seen as a crucial parameter for the safety running of the HLW disposal. Due to the tremendous amount of heat released by such waste, the thermal conductivity of the buffer material is a crucial parameter for the safety running of the high-level radioactive waste disposal. For the purpose of improving its thermal conductivity, this research used the graphene oxide (GO) to modify the pure bentonite and then the nanocarbon-based bentonite (GO-GMZ) was obtained chemically. The thermal conductivity of this modified soil has been measured and investigated under various conditions in this study: the GO content, dry density, and water content. Researches confirm that the thermal conductivity of the modified bentonite is codetermined by the three conditions mentioned above, namely, the value of GO content, dry density, and water content. Besides, the study proposes an improved geometric mean model based on the special condition to predict the thermal conductivity of the compacted specimen; moreover, the calculated values are also compared with the experimental data.

Design Options for HLW Repository Operation Technology: Part V—Preliminary Study and Small Scale Experiments on the Method of Removal of Buffer Material With Salt Solution

2010 ◽  
Author(s):  
Satohito Toguri ◽  
Takashi Ishii ◽  
Jiho Jang ◽  
Mitsunobu Okihara ◽  
Kengo Iwasa ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Salt Solution ◽  
Scale Model ◽  
Disposal Site ◽  
Small Scale ◽  
High Level Radioactive Waste ◽  
Buffer Material ◽  
Basic Characteristics ◽  
High Level ◽  
Design Options

The Nuclear Safety Commission of Japan stipulates that “When closing a waste disposal site, the validity of safety assessment results should be verified using the data obtained in the construction and operation phases as well. The retrieval of high-level radioactive waste should be made continuously possible during the period before the verification of the validity.”[1] Retrieving high-level radioactive waste requires the removal of the bentonite-based buffer around the emplaced overpack. In this study, focus was placed on a method for reducing the cohesion of bentonite, a major component of the buffer by dipping the buffer in fluid salt solution and dissolving the material into a slurry using fluid salt solution for removal (method of making a slurry). In order to examine the feasibility and the basic characteristics of the method, element tests were conducted using a small specimen of buffer and fluid salt solution (NaCl solution). In order to verify the feasibility of the infiltration and jetting of fluid salt solution, small-scale model tests were conducted using a specimen composed of 1/14-scale overpack and buffer. It was made clear that the infiltration and jetting of fluid salt solution was feasible as a method for removing a buffer.

Swelling characteristics of bentonites in artificial seawater

2009 ◽  
Vol 46 (2) ◽  
pp. 177-189 ◽  
Author(s):  
Hideo Komine ◽  
Kazuya Yasuhara ◽  
Satoshi Murakami
Keyword(s):  
Radioactive Waste ◽  
Swelling Pressure ◽  
Radioactive Waste Disposal ◽  
Exchangeable Cation ◽  
Deformation Characteristics ◽  
High Level Radioactive Waste ◽  
Disposal Facility ◽  
Buffer Material ◽  
Swelling Characteristics ◽  
High Level

Bentonite is currently designated for use as a buffer material for the repository of high-level radioactive waste because such a material requires swelling characteristics to seal the waste. A high-level radioactive waste disposal facility may be built in a coastal area of Japan because transportation of this waste by ships is feasible. Therefore, it is important to investigate the effects of seawater on a bentonite-based buffer. This study is intended to investigate the influence of seawater on the swelling pressure and swelling deformation characteristics of five common types of bentonite. The experiments described herein clarify the relations between the influence of seawater grade and compaction density, type of exchangeable cation, montmorillonite content of the bentonite, and vertical pressure condition. Based on experimental results, suitable specifications have been defined for a bentonite-based buffer that can withstand the effects of seawater.

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