NDTsi 2001 Session: Major Component Inspection I-IV
Thermal Crackling Detection and Sizing on Thermal Barriers of Primary Pumps
E. Abittan, EDF, France; D. Desruelles, Framatome-ANP; B. Pierrot, CTE Nordtest, France
ABSTRACT
Thermal crackling occurs on the thermal barrier flange lower surface of primary pumps. EDF has defined a repair strategy, which is currently applied. Besides, EDF in collaboration with FRAMATOME ANP has led a NDE evaluation program for the detection and sizing of such defects. The main difficulties of this NDE problem are due to the flange geometry and the toric inspection surface, the material thickness, about 200 millimetres and its austenitic nature, which can lead to ultrasonic backscatttered noise and beam deviation, and the defect morphology. Moreover, for in-service inspection objectives, the ultrasonic probes have to be integrated in the limited space between the flange and the casing, leading to strong stresses on the probe conception and manufacturing. To reach the detection and sizing objectives and to separate the effects of these above parameters, the evaluation program has been realised following different stages: technical justification for the UT techniques to develop, beam simulation and justification for the probe, ferritic and austenitic representative mock-up manufacturing for the acoustic parameters evaluation. Development methodology, UT techniques and main results of this evaluation program are discussed in this paper.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
