|
Tomas Paces, Czech Geological Survey (Czech Republic)
Vladimir Blaha, Czech Geological Survey (Czech Republic)
Lenka Rukavickova, Czech Geological Survey (Czech Republic)
|
|
A test hole to 350 m were drilled in compact fractured granite. The mineralogical and chemical composition of the granite did not exhibit any significant variations. The hydraulic conductivity coefficients decreased with depth and their range was from 5.1E-8 to 1.4E-10 m/s. Six months after the tests, the hole was equipped with packers to isolate 4 depth sections. Very small quantities of ground water were withdrawn monthly from the sections and analyzed. It was found that the drilling and hydraulic tests disturbed the chemical composition of groundwater. The concentrations of major, minor and trace dissolved components reached a steady state after various times following the six month period after the testing was terminated . Each of the chemical components behaved differently in the individual isolated sections of the drill hole. The time to achieve steady state took from few days to more than 800 days. The examples of the temporal trends include dissolved Na, Ca, SO4, HCO3, Fe, Mn, Zn, Cu, Cr, Mo and organic carbon. The character and possible causes for the observed trends are discusses. Determination of stable chemical composition of ground water in rocks to be selected for future deep repository of nuclear spent fule is needed for safety assesment of the repository functions.
|
