Jin-Seop Kim

PROPERTIES OF LOW-PH CEMENT GROUT AS A SEALING MATERIAL FOR THE GEOLOGICAL DISPOSAL OF RADIOACTIVE WASTE

The current solution to the problem of using cementitious material for sealing purposes in a final radioactive waste repository is to develop a low-pH cement grout. In this study, the material properties of a low-pH cement grout based on a recipe used at ONKALO are investigated by considering such factors as pH variation, compressive strength, dynamic modulus, and hydraulic conductivity by using silica fume and micro-cement. From the pH measurements of the hardened cement grout, the required pH (＜ pH 11) is obtained after 130 days of curing. Although the engineering properties of the low-pH cement grout used in this study are inferior to those of conventional high-pH cement grout, the utilization of silica fume and micro-cement effectively meets the long-term environmental and durability requirements for cement grout in a radioactive waste repository.

R&D Review on the Gap Fill of an Engineered Barrier for an HLW Repository

Abstract I n a high-level waste repository, the gap fill of the engineered barrier is an important component that influences the performance of the buffer and backfill. This paper reviewed the overseas status of RD blowing through the use of shotcrete technology and auger placement and compaction techniques have been used in the gap of horizontal deposition hole and tunnel. However, these emplacement techniques are still technically at the beginning stage, and thus additional research and development are expected to be needed.

Damage Assessment of Two-Mica Granite under Uniaxial Cyclic Incremental Loading Using Acoustic Emission

In this study, damage assessment of granite under uniaxial cyclic incremental loading was analyzed by the acoustic emission (AE) techniques and the obtained results were compared with stress-strain curve data. As the loading cycle number increased, the dissipated energy result obtained from stress-strain curve was only shown the rock samples were gradually damaged, then damage degree increased 0.23 to 0.48 from the 5th cyclic loading in stress-strain curve data. AE energy result also began to increase the damage degree dramatically at the same stage and it was similar to the result of dissipated energy. Thus, AE result was correlated with dissipated energy measurement and it was highly correlated (

Propagation and Interactions of Acoustic Waves in a Waveguide Attached at the Surface of Rock

Measurements of the dynamic response of a rock mass are inevitable in the systematic long-term monitoring and the maintenance of the radioactive waste disposal repository. With this point of view, AE (acoustic emission) detection is considered to be a promising technique for monitoring the in-situ performance of a rock mass. In this study, the propagation and interactions of guided acoustic waves in a waveguide connector, which is required in an in-situ application of an AE monitoring system were investigated and the coupling methods of a waveguide to the surface of rock mass were compared. The changes in acoustic wave amplitude, time delay, frequency variation, and system transfer function were measured between the waveguide and a rock sample. Subsequently the waveguide coupling conditions filled with epoxy were compared with a mechanical type of coupling for the validity of field application. The results derived from this study can be valuable information for the quantitative analysis of signal processing in AE source localization and the degree of crack damage in a radioactive waste repository.© 2010 ASME