Argillaceous rock as host rock for final storage of radioactive waste in Germany

On behalf of the German Federal Ministry for Economics and Technology (BMWi), the Federal Institute for Geosciences and Raw Materials (BGR) in a study described argillaceous rock formations as potential host rock for repositories in some areas of Germany, and evaluated them. The study was based on available and usable data derived from maps, archives, and approx. 25,000 drillings. No additional field tests or laboratory examinations were conducted. The study was published in April 2007 under the title of "Untersuchung und Bewertung von Tongesteinsformationen" (www.bgr.bund.de). The exclusion criteria and minimum requirements recommended by the Working Group on Repository Sites (AkEnd) in 2002 served as a basis for defining the subareas eligible for further study. In addition, internationally acknowledged selection criteria as well as weighting criteria to be taken into account especially under German conditions were applied. The result of the study is not a representation of repository sites. However, the investigations show that argillaceous rock meeting host rock requirements occurs in the Lower Cretacious as well as in rock formations of the Lower and Middle Jurassic of Northern Germany. In Southern Germany, rock of the Middle Jurassic was found to be worthy of examination. The clay formations of the Tertiary are not considered in the study because of their relatively adverse mechanical properties in Germany. The areas highlighted are situated mainly in Lower Saxony, Mecklenburg-Western Pomerania, Saxony-Anhalt, Baden-Wurttemberg and, to a lesser extent, also in Bavaria, Brandenburg, and North Rhine-Westphalia. Other regional restrictions are mentioned in the study. Any further assessment of the argillaceous rock in the study would require an extensive program of investigations with a view to selecting sites for the final storage of high-level radioactive waste.