A General-purpose Device Was Used to Successfully Displace Cracks in Underground Rock for the First Time in the World
—Significant Progress Toward a Wide Varity of Underground Utilization—

In geological disposal of high-level radioactive waste, it is required to consider the possibility that diastrophism or the like may displace underground cracks, which increases the permeability of such cracks and affects the confinement capability of geologic formations. In considering this possibility, it is effective to conduct an experiment to artificially displace actual underground cracks. The existing test method involved disadvantages in the practical aspect; for example, it required a high cost and a great deal of time to arrange equipment specifically designed for observing displacement of cracks during the experiment and the displacement amounts that can be observed with such equipment is limited (to several millimeters).

As a new method, the Japan Atomic Energy Agency came up with a practical test method for displacing cracks using a general-purpose testing device that had been traditionally used for different testing. In verification testing, displacements (of several centimeters) were observed that were larger than those that can be observed with the specifically designed device.

The testing has revealed that such large displacements cause no significant changes in permeability.

This method is expected to be not only used for geological disposal or underground storage of CO2 but also help solve problems in the fields associated with various underground applications such as mine development and anti-disaster measures for slopes.