2015:47 GEMA-Site 1: Model description and example application


In 2011 the Swedish Nuclear Fuel and Waste Management Company (SKB) submitted an assessment of the long-term safety of a KBS-3 geological disposal facility for spent nuclear fuel in Forsmark, Sweden. This assessment, the SR-Site project, supports the licence application of SKB to build such a final disposal facility. The biosphere dose assessment carried out as part of SR-Site features a highly detailed model of the evolution of the landscape in Forsmark area. The Forsmark site is located on the Baltic coast with a terrestrial landscape including lakes, mires, forest and arable land. The land at the site is projected to continue to rise due to post-glacial uplift (legacy climate change from the previous deglaciation) leading to significant ecosystem transitions over the next ten to twenty thousand years. SKB’s biosphere model is built on a landscape evolution model, whereby radionuclide releases to distinct hydrological basins/sub-catchments (termed “objects”) are represented as they evolve through land rise.


The objective of the study is to develop an alternative evolving dose assessment model that is simple but includes relevant details of local characteristics, particularly in respect of changes to the near-surface hydrology during land rise. The developed model, GEMA-Site, is used by SSM to investigate uncertainties associated with the modelling of the future Forsmark landscape in the context of long timescale radiological assessment.