Pretest fracture assessment of the NESC-1 spinning cylinder under a PTS transient

Abstract This report presents pretest fracture assessments of the NESC-1 spinning cylinder. The clad cylinder has an internal diameter of 1045 mm, a wall thickness of 175 mm and a length of 1296 mm. An internal surface breaking crack with a depth of 73 mm and a length of 205 mm subjected to a thermal shock is studied. Three-dimensional elastic-plastic finite element calculations, considering the crack-tip constraint, are employed in the assessments. Also performed are sensitivity studies to demonstrate how different affecting factors, especially the cladding residual stresses, impact the crack driving force. It is found that the crack front conditions in the cladding and at the deepest point of the crack are far from critical, but cleavage fracture events can be expected in the cladding HAZ. The results show substantial loss of crack-tip constraint in the cladding HAZ compared with the SSY solutions. From the sensitivity studies, it is observed that uncertainties due to different assumptions in the analysis influence the assessment results less than uncertainties in the fracture toughness data of the materials.

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