Displacement Prediction Possibilities from Bátaapáti Radwaste Repository

Abstract

The program for the final disposal of low and intermediate level radioactive waste was established by Paks Nuclear Power Plant, Hungary. Preparation of final disposal has been done as part of a national program since 1993. The Central Nuclear Financial Fund and the Public Limited Company for Radioactive Waste Management (Puram) have been established to coordinate organizations and activities for all tasks in connection with nuclear waste treatment. The project was started with a geological screening in order to find the most suitable geological formation for radioactive waste repository. The selected potential host rock is a granite complex in the Mórágy Granite Formation in the south-western part of Hungary, close to the village of Bátaapáti.In the underground facility different measuring systems have been used (extensometers, inclinometers, convergence measurements), requiring a transformation into radial and tangential displacements. Until now not much emphasis was laid on the 3D geodetical displacement monitoring measurements or on the use of advanced methods such as the evaluation of displacement vector orientations.The final survey results are ensured by the Mecsekérc Ltd. Department of Geodesy as a daily actualized database with Unified National Projection system (EOV) coordinates. Upon request the surveyors provide data in local coordinates (they provide relative and absolute coordinates simultaneously), allowing a meaningful analysis. The aim of this paper is to shortly introduce the surveying process and interpretation of the 3D optical displacement measurement methodology. Our research is related to geodetic measurements which were carried out in the repository chambers and some exploratory tunnels. The mentioned exploratory tunnels crossed through fault zones. We have studied the effect of the fault zones on the measured 3D displacements, using the common evaluation and displacement prediction methodologies, and we show the results obtained during the control of the “normality” of the displacements from the underground spaces which were excavated full face and at larger sections by top heading and bench method. The results of the presented case studies show that the 3D optical displacement monitoring enables the prediction of the geotechnical conditions ahead of the face and the influence of fault zones located outside of the excavated space.