Groundwater flow modeling of periods with periglacial and glacial climate conditions for the safety assessment of the proposed high-level nuclear waste repository site at Forsmark, Sweden

Vidstrand, Patrik; Follin, Sven; Selroos, Jan-Olof; Näslund, Jens-Ove

Groundwater flow modeling of periods with periglacial and glacial climate conditions for the safety assessment of the proposed high-level nuclear waste repository site at Forsmark, Sweden | Modélisation des écoulements d’eau souterraine avec des conditions climatiques périglaciaires et glaciaires pour l’évaluation de la sureté du site de dépôt proposé pour les déchets nucléaires de haut niveau à Frosmark, Suède Modelado de flujo de agua subterránea en períodos con condiciones climáticas glaciales y periglaciales para la evaluación de la seguridad del sitio propuesto para un repositorio de residuos nucleares de alta actividad en Forsmark, Suecia 瑞典福什马克高强度核废料储藏地安全评价中冰缘及冰川气候条件下的地下水流模拟 Modelação de fluxo de águas subterrâneas em períodos de condições climáticas periglaciais e glaciais para avaliação da segurança do proposto depósito de resíduos nucleares de alta atividade em Forsmark, Suécia

2014

Vidstrand, Patrik | Follin, Sven | Selroos, Jan-Olof | Näslund, Jens-Ove

The impact of periglacial and glacial climate conditions on groundwater flow in fractured crystalline rock is studied by means of groundwater flow modeling of the Forsmark site, which was recently proposed as a repository site for the disposal of spent high-level nuclear fuel in Sweden. The employed model uses a thermal-hydraulically coupled approach for permafrost modeling and discusses changes in groundwater flow implied by the climate conditions found over northern Europe at different times during the last glacial cycle (Weichselian glaciation). It is concluded that discharge of particles released at repository depth occurs very close to the ice-sheet margin in the absence of permafrost. If permafrost is included, the greater part discharges into taliks in the periglacial area. During a glacial cycle, hydraulic gradients at repository depth reach their maximum values when the ice-sheet margin passes over the site; at this time, also, the interface between fresh and saline waters is distorted the most. The combined effect of advances and retreats during several glaciations has not been studied in the present work; however, the results indicate that hydrochemical conditions at depth in the groundwater flow model are almost restored after a single event of ice-sheet advance and retreat.

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