Reducing Condition Surveys around the Underground Cavern by Measurements of pH and Self-potential

Abstract

 Around the testing cavern of the subsurface disposal program of low level radioactive wastes in Rokkasho-mura, Aomori Prefecture of Japan, some surveys on the reducing environment assessment have been carried out in the Neogene sedimentary rocks. Through the hand drilling groundwater quality measurement and the self-potential measurement, the measurements of pH and self-potential are considered to be an effective method in the geochemical survey to evaluate the oxidation-reduction condition of the underground. The values of the pH and self-potential did not have a great variability, and had a stable profile in a few measurements. Thus, these items are important in the long-term monitoring of the underground environment. The classification of the reducing condition into some regions could induce a different aspect of the deep underground geochemical environment, and lead to the distribution of the reduction condition or damaged zone of the excavated rock mass.