LOCAs with release of insulation material: generic aspects and international solutions

Abstract

Abstract In case of a LOCA within the containment the released water/steam jet can fragment insulation material from the leaking pipe and from pipes in the neighborhood. The released insulation material and other materials like e.g. dust and paint chips are washed into the sump. A part of this debris reaches the sump strainers after starting ECCS pumps. Some material will be retained by the strainers depending on the mesh size or hole diameter of the strainers. The residual material penetrates the strainers and reaches downstream components and especially fuel elements. Therefore it has to be demonstrated that fuel elements are sufficiently cooled after LOCAs with release of insulation material and other materials. Several events since 1992 have shown the possibility of strainer clogging. This article discusses generic aspects and some international approaches to sump clogging issue and related tasks. An overview of the status quo and comparison of different approaches and background is given.