HR: 14:00h
AN: IA33A-01    [Abstracts]
TI: Characterization of Discharge Areas of Radionuclides Originating From Nuclear Waste Repositories
AU: * Marklund, L
EM: larsmark@kth.se
AF: The Royal Institute of Technology, Teknikringen 76, Stockholm, 100 44, Sweden
AU: Xu, S
EM: shulan.xu@ssm.se
AF: Swedish Radiation Safety Authority, Stralsakerhetsmyndigheten, Stockholm, 171 16, Sweden
AU: Worman, A
EM: worman@kth.se
AF: The Royal Institute of Technology, Teknikringen 76, Stockholm, 100 44, Sweden
AB: If leakages in nuclear waste repositories located in crystalline bedrock arise, radionuclides will reach the biosphere and cause a risk of radiological impact. The extent of the radiological impact depends on in which landscape elements the radionuclides emerge. In this study, we investigate if there are certain landscape elements that generally will act as discharge areas for radionuclides leaking from subsurface deposits. We also characterize the typical properties that distinguish these areas from others. In humid regions, landscape topography is the most important driving force for groundwater flow. Because groundwater is the main transporting agent for migrating radionuclides, the topography will determine the flowpaths of leaking radionuclides. How topography and heterogeneities in the subsurface affect the discharge distribution of the radionuclides is therefore an important scope of this study. To address these issues, we developed a 3-D transport model. Our analyses are based on site-specific data from two different areas in Sweden, Forsmark, Uppland, and Oskarshamn, Småland. The Swedish Nuclear Waste Management Company (SKB) has selected these two areas as candidate areas for a deep repository of nuclear waste and the areas are currently subject to site investigations. Our results suggest that there are hot-spots in the landscape i.e. areas with high probability of receiving large amounts of radionuclides from a leaking repository of nuclear waste. The hot-spots concentrate in the sea, streams, lakes and wetlands. All these elements are found at lower elevations in the landscape. This pattern is mostly determined by the landscape topography and the locations of fracture zones. There is a relationship between fracture zones and topography, and therefore the importance of the topography for the discharge area distribution is not contradicted by the heterogeneity in the bedrock. The varieties of landscape elements which have potential for receiving significant amounts of radionuclides are limited. To limit the radiological dose assessment, analyses should be focused to and more detailed in such landscape areas in which doses are expected to be high. Due to the similarities among deep groundwater discharge areas, one can make site-specific analyses of those areas, which have a broad applicability for migration of radionuclides originating from a nuclear waste repository.
DE: 1829 Groundwater hydrology
DE: 1847 Modeling
DE: 3252 Spatial analysis (0500)
DE: 8010 Fractures and faults
SC: International Association of Hydrogeologists, Canadian National Chapter [IA]
MN: 2009 Joint Assembly