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Title: Preliminary Safety Analysis of the Gorleben Site: Geological Database - 13300

Abstract

The Gorleben salt dome is 4 km wide and nearly 15 km long. It is composed of different salt rock types of the Zechstein (Upper Permian) series and extends to the Zechstein basis in a depth of more than 3 km. In the course of the salt dome formation the salt was moved several kilometers. During the uplift of the salt the initially plane-bedded strata of the Zechstein series were extensively folded. In this process anhydrite as a competent layer was broken to isolated blocks. In the core of the salt dome the Hauptsalz, which is characterized by a particularly high creeping capacity, forms a homogeneous halite body with a volume of several cubic kilometres. The Hauptsalz contains gaseous and liquid hydrocarbons in separated zones of decimeter to meter dimensions. The overall hydrocarbon content is far below 0.01 %. At the flanks the salt dome consists of salt rocks with lower creeping capacities. Brine reservoirs with fluid volumes in the range of liters to hundreds of cubic meters exist in certain regions of this part of the salt dome. The water content of the Hauptsalz is below 0.02 %. Interconnected pores do not exist in the salt rock outside ofmore » fluid bearing or fractured areas, i.e. the salt rock is impermeable. The exploration of the Gorleben site as a potential site for a HLW-repository started in 1979 and is still in progress. To date no scientific findings contest the suitability of the site for a safe HLW-repository. (authors)« less

Authors:
; ; ;  [1]
  1. Federal Institute for Geosciences and Natural Resources (BGR), 30655 Hannover, Stilleweg 2 (Germany)
Publication Date:
Research Org.:
WM Symposia, 1628 E. Southern Avenue, Suite 9-332, Tempe, AZ 85282 (United States)
OSTI Identifier:
22225032
Report Number(s):
INIS-US-13-WM-13300
TRN: US14V0486045987
Resource Type:
Conference
Resource Relation:
Conference: WM2013: Waste Management Conference: International collaboration and continuous improvement, Phoenix, AZ (United States), 24-28 Feb 2013; Other Information: Country of input: France; 4 refs.
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 58 GEOSCIENCES; ANHYDRITE; CREEP; GEOTHERMAL EXPLORATION; GORLEBEN SALT DOME; HALITE; HIGH-LEVEL RADIOACTIVE WASTES; HUMIDITY; HYDROCARBONS; LIQUIDS; ROCKS; SAFETY ANALYSIS; SALTS

Citation Formats

Weber, Jan Richard, Mrugalla, Sabine, Dresbach, Christian, and Hammer, Joerg. Preliminary Safety Analysis of the Gorleben Site: Geological Database - 13300. United States: N. p., 2013. Web.
Weber, Jan Richard, Mrugalla, Sabine, Dresbach, Christian, & Hammer, Joerg. Preliminary Safety Analysis of the Gorleben Site: Geological Database - 13300. United States.
Weber, Jan Richard, Mrugalla, Sabine, Dresbach, Christian, and Hammer, Joerg. Mon . "Preliminary Safety Analysis of the Gorleben Site: Geological Database - 13300". United States. doi:.
@article{osti_22225032,
title = {Preliminary Safety Analysis of the Gorleben Site: Geological Database - 13300},
author = {Weber, Jan Richard and Mrugalla, Sabine and Dresbach, Christian and Hammer, Joerg},
abstractNote = {The Gorleben salt dome is 4 km wide and nearly 15 km long. It is composed of different salt rock types of the Zechstein (Upper Permian) series and extends to the Zechstein basis in a depth of more than 3 km. In the course of the salt dome formation the salt was moved several kilometers. During the uplift of the salt the initially plane-bedded strata of the Zechstein series were extensively folded. In this process anhydrite as a competent layer was broken to isolated blocks. In the core of the salt dome the Hauptsalz, which is characterized by a particularly high creeping capacity, forms a homogeneous halite body with a volume of several cubic kilometres. The Hauptsalz contains gaseous and liquid hydrocarbons in separated zones of decimeter to meter dimensions. The overall hydrocarbon content is far below 0.01 %. At the flanks the salt dome consists of salt rocks with lower creeping capacities. Brine reservoirs with fluid volumes in the range of liters to hundreds of cubic meters exist in certain regions of this part of the salt dome. The water content of the Hauptsalz is below 0.02 %. Interconnected pores do not exist in the salt rock outside of fluid bearing or fractured areas, i.e. the salt rock is impermeable. The exploration of the Gorleben site as a potential site for a HLW-repository started in 1979 and is still in progress. To date no scientific findings contest the suitability of the site for a safe HLW-repository. (authors)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jul 01 00:00:00 EDT 2013},
month = {Mon Jul 01 00:00:00 EDT 2013}
}

Conference:
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  • Exploration work at the Gorleben salt dome has been carried out since 1977 to investigate the site regarding its suitability as a final repository for high-level radioactive wastes. In the framework of the 'Preliminary Safety Analysis of the Gorleben Site' a comprehensive assessment is being performed with focus on long-term safety. Because the integrity of the geological barrier is crucial for protection from damage caused by ionising radiation during the post-operational phase, 2D and 3D thermo-mechanical calculations for a reference section through the salt dome were carried out, all looking at two different waste emplacement concepts: emplacement in drifts andmore » in boreholes. The calculated stresses are the basis for evaluating the barrier integrity on the basis of the dilatancy criterion and the fluid pressure criterion. (authors)« less
  • Based upon the German safety criteria, released in 2010 by the Federal Ministry of the Environment (BMU), a safety concept and a safety assessment concept for the disposal of heat-generating high-level waste have both been developed in the framework of the preliminary safety case for the Gorleben site (Project VSG). The main objective of the disposal is to contain the radioactive waste inside a defined rock zone, which is called containment-providing rock zone. The radionuclides shall remain essentially at the emplacement site, and at the most, a small defined quantity of material shall be able to leave this rock zone.more » This shall be accomplished by the geological barrier and a technical barrier system, which is required to seal the inevitable penetration of the geological barrier by the construction of the mine. The safe containment has to be demonstrated for probable and less probable evolutions of the site, while evolutions with very low probability (less than 1 % over the demonstration period of 1 million years) need not to be considered. Owing to the uncertainty in predicting the real evolution of the site, plausible scenarios have been derived in a systematic manner. Therefore, a comprehensive site-specific features, events and processes (FEP) data base for the Gorleben site has been developed. The safety concept was directly taken into account, e.g. by identification of FEP with direct influence on the barriers that provide the containment. No effort was spared to identify the interactions of the FEP, their probabilities of occurrence, and their characteristics (values). The information stored in the data base provided the basis for the development of scenarios. The scenario development methodology is based on FEP related to an impairment of the functionality of a subset of barriers, called initial barriers. By taking these FEP into account in their probable characteristics the reference scenario is derived. Thus, the reference scenario describes a comprehensive set of probable future evolutions of the repository site. By stepwise consideration of less probable FEP or less probable characteristics of FEP within this process, alternative scenarios are also developed, which are characterized by a lower probability of occurrence. An important methodological aspect is that some assumptions had to be made for the scenario development. They allow, on the one hand, to deal systematically with incomplete knowledge regarding the geological situation below ground owing to restricted site investigations, and, on the other hand, to structure the scenario development process. The consideration of alternative assumptions may result in additional alternative scenarios. (authors)« less
  • The project preliminary safety analysis of the Gorleben site started in 2010 and is based on the safety requirements for heat generating radioactive waste released from the German Federal Ministry for Environment, natural conservation and nuclear safety. The project consists of several tasks: the database defining the geology of Gorleben and the composition of the waste to be disposed of, the safety and demonstration concept, the repository concepts, the scenario analysis, the system analysis with long-term safety assessment and the synthesis. The overall synthesis indicates presently the compatibility of a repository in Gorleben with the safety requirements. The application ofmore » the method for a site selection process is still under evaluation. (authors)« less
  • Rock salt is one of the possible host rock formations for the disposal of high-level radioactive wastes in Germany. The Preliminary Safety Analysis of the Gorleben Site (Vorlaeufige Sicherheitsanalyse Gorleben, VSG) evaluates the long-term safety of a hypothetical repository in the salt dome of Gorleben, Germany. A mature repository concept and detailed knowledge of the site allowed a detailed process analysis within the project by numerical modeling of single-phase and two-phase flow. The possibility of liquid transport from the shafts to the emplacement drifts is one objective of the present study. Also, the implications of brine inflow on radionuclide transportmore » and gas generation are investigated. Pressure build-up due to rock convergence and gas generation, release of volatile radionuclides from the waste and pressure-driven contaminant transport were considered, too. The study confirms that the compaction behavior of salt grit backfill is one of the most relevant factors for the hydrodynamic evolution of the repository and the transport of contaminants. Due to the interaction between compaction, saturation and pore pressure, complex flow patterns evolve. Emplacement drifts serve as gas sinks or sources at different times. In most calculation cases, the backfill reaches its final porosity after a few hundred years. The repository is then sealed and radionuclides can only be transported by diffusion in the liquid phase. Estimates for the final porosity of compacted backfill range between 0 % and 2 %. The exact properties of the backfill regarding single- and two-phase flow are not well known for this porosity range. The study highlights that this uncertainty has a profound impact on flow and transport processes over long time-scales. Therefore, more research is needed to characterize the properties of crushed salt grit at low porosities or to reduce the adverse effects of possible higher porosities by repository optimization. (authors)« less
  • In the Federal Republic of Germany, the disposal of radioactive waste is being planned for deep geologic formations only. A repository will be constructed in the Gorleben salt dome for all kinds of radioactive waste, in particular, heat-generating waste from reprocessing and spent fuel. Pusuant to German safety criteria, a detailed site characterization program including above-ground and underground investigations must be performed to provide all necessary data for the site-specific safety assessment.