Hydride reorientation in fuel cladding under interim storage conditions with low hoop stress

Abstract. The restart of the search for a final repository high-level nuclear waste in Germany and resulting so-called white map lead to reassessment safety interim storage as well. Due increase periods with prospected timescale until 2068, among other things, renewed consideration cladding tube integrity is required handling fuel assemblies during repackaging into containers. Besides oxide formation operation, hydrides can have negative influence on stability later on. hydrides, which are initially precipitated tangentially material reorient result temperature load history precipitate again radial direction cooling under load. In recent years, number investigations already been carried out respect this topic, conditions that present high burn-up corresponding hydrogen contents. these cases, reorientation effects did occur stresses be encountered storage, but proportions were very low classified not being harmful. addition tests tubes containing contents, sporadic contents also out, example, by Hardie Shanahan (1975) Chu et al. (2008). These indicated strong could because complete dissolution tensile stress. Kaufholz (2018) formulated hypothesis describes effect consequence free nucleation without presence precipitates. This results possible extremely pronounced even extend through wall. residual hinder precipitation or represent preferential points absent. confirm behaviour. They show massive reorientations at lower end literature values that, now, interpreted uncritical. Considering hysteresis solubility between terminal solid (TSSD) (TSSP), it becomes apparent 100 ppmw (parts per million weight) starts approx. 538 K radially stress 52 MPa form hydrides. need further research, since thermal mechanical loads well below permissible limit expected so far. applies particular materials either absorb less operation only burn-ups. study provides an overview status quo, presents part project MUDZ (Modellierung und Untersuchung der Degradation von Hüllrohrmaterialien aus Zr-Legierungen durch Hydridbildungs- Hydridverteilungsprozesse im Hinblick auf die Langzeitzwischenlagerung) KEK (Kompetenzerhalt Kerntechnik) initiative obtained, discusses ramifications results.