Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: Creep-fatigue crack initiation assessment on thick circumferentially notched 316L tubes under cyclic thermal shocks and uniform tension with the sigmad approach

Michel, B.; Poette, C. (CEA Centre d'Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France))

Abstract

For crack initiation assessment under creep fatigue loading, in high temperature Fast Reactor's components, specific approaches based on fracture mechanics analysis had to be developed. In the present paper the crack initiation assessment method proposed in the A16 document is presented. The so called ''sigmad method'' is also validated on experimental results for tubular specimens with internal axisymmetric surface cracks. Experimental data are extracted from the TERFIS program carried out on a sodium test device at the CEA Cadarache. Metallurgical examinations on TERFIS specimens confirm that the initiation assessment of the ''sigmad'' approach is conservative even for a different geometry than the CT specimen on which the method was set up. However, the conservatism is reduced when the creep residual stress field is relaxed during the hold time. An investigation concerning this last point is needed in order to know if relaxing the stress, when using a lower bound of the mechanical properties, always keeps a safety margin.

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key words: Fast Neutron Spectrum Systems, Nuclear Technology
Reference:
Creep-fatigue damage rules for advanced fast reactor design. Technical committee meeting, Manchester (United Kingdom). 11-13 Jun 1996
International Atomic Energy Agency, Vienna (Austria)
IAEA-TECDOC--933, pp:117-129