A brief literature review has been made with respect to imperviousness of reinforced concrete structures. Both diffusivity and permeability of reinforced concrete related to gas and liquid penetration are covered, without focus on any specific gas or liquid. This report gives an overview of factors that may affect the tightness, especially related to cracks and low temperatures. The report also summarizes mechanical and thermal properties of reinforced concrete at low temperatures. Properties at low temperatures that somehow may affect the imperviousness of a reinforced concrete structure are implemented, specially related to possible influence on development of cracks.To achieve a impervious concrete structure, it is assumed that the main challenge is to avoid crack formation. This can be achieved by a combination of proper structural design and materials technology. If the structure is exposed to cryogenic temperatures, special considerations must be taken due to prevent development of cracks. Most likely it will be important to see this project in relation with the material approach in COIN P1 (advanced cementing materials) and COIN P2 (improved construction technology) with respect to tight concrete structures. The content in this report is a result of a preliminary study finished within limited time and resources. The conclusion (Ch. 6) may be used as a basis for planning of further research. The report must not be considered as a complete state of the art. In further work it is also necessary to make more specific primary objective regarding to function and acceptance criterion.