Prediction of ‘effective’ corrosion rates by in-situ internal pressure creep testing in LBE for Ti-stabilised DIN 1.4970 (15-15Ti) austenitic stainless steel cladding tubes

Abstract

ABSTRACT In this paper, a new high-temperature methodology for determining the ‘effective’ corrosion rates of internal pressure-tested cladding tubes, based on the reduced creep failure times under exposure, is presented. The methodology has been developed to estimate the combined damage accumulation of corrosion and creep and to establish temperature limits for the use of 1515Ti claddings in high-temperature Lead-Bismuth-Eutectic (LBE). The results are compared to static corrosion rates determined from earlier test campaigns in stagnant LBE. All tests are conducted on 24% cold worked 1515Ti cladding tubes that are the SCK CEN reference material for the MYRRHA design efforts. The virgin material creep model that is the basis for the corrosion rate estimation, has been fitted on an extended creep failure database and a life-fraction rule is applied to accommodate for the life reduction caused by the sought ‘constant’ effective corrosion rate.