A16: guide for defect assessment at elevated temperature

摘要

A large program has been performed in France in order to develop, for the design and operation of High Temperature Reactor plants, defect assessment and Leak-Before-Break (LBB) procedures. As a result of the collaboration between CEA, EdF and Framatome, the A16 guide is now included in the RCC-MR 2002 edition. The main defect assessment procedures proposed in this A16 guide are:fatigue or creep-fatigue crack initiation based on the sigma_d method, fatigue crack growth,creep-fatigue crack growth,ductile tear initiation and propagation,together with a LBB assessment.The calculations of the fracture mechanic parameters J and C (t) for plates, pipes, elbows, etc. and laboratory specimens under mechanical loading and thermal shock are based on new formulations of the reference stress and new K_1 handbooks for a large panel of geometries containing surface and through-wall defects. Some guidance on the experimental test methods for measuring the fracture mechanics properties of the materials are also included in the document. The procedures and analytical solutions of the A16 guide are consistent with those proposed at moderate temperature by the RSE-M for PWRs and cover also elevated temperature where creep is significant.