Development and production mastering of cold-formed heat-exchange tubes for NPP steam generators made of austenitic steels at Cybersteel LLC

Heat exchange tubes for steam generators of NPPs with WWER reactors are the most metal-intensive and loaded element of the steam generator and serve as a barrier between the radioactive coolant of the primary circuit and the safe steam of the secondary circuit. The integrity of the metal of these tubes directly determines the nuclear and radiation safety of the NPP. To act as an effective barrier, the heat exchange tubes of the steam generator must be free of cracks, corrosion and thinning. One of the mandatory requirements for the quality of heat exchange tubes is 100 % non-destructive eddy current testing to detect hidden defects on the tubes that form both during the manufacture of the tubes and defects that may appear during the operation of steam generators. There are problems with the reliability of the obtained eddy current testing results associated with the complexity of the analysis of eddy current signals due to the presence of interfering factors. One of the main interfering factors in the automatic and expert processing of eddy current testing signals is geometric noise (Pilger noise). The nature of geometric noise is related to the peculiarity of cold rolling of heat exchange tubes on cold rolling mills. Cyberstal LLC has developed and mastered a method for producing cold-formed heat exchange tubes for NPP steam generators from austenitic steels with a low level of geometric noise.