Nondestructive Evaluation of Steam Generator Tubes

Abstract

The Steam Generator Tube Integrity Program at Argonne National Laboratory is developing a method for determining when the steam generator tubes are flawed without necessitating the removal and destruction of the generator tubes in question. A system is being developed to test the tubes in place as they cannot be easily removed in a real reactor. The steam generator tubes are set in a testing rack to imitate the situation within a reactor. There are a variety of reasons why a new system would be beneficial to both the environment and the power companies. If such a system can be implemented in a remote fashion, contact with any contaminants and other undesirable by products of nuclear fission will be minimized. Such a procedure could be either computer automated or manual, but would have to identify which tubes have flaws and should be replaced before a disaster occurs. Commonly, tubes with identified flaws are plugged and only the "good" ones are used. However, this greatly reduces the generator efficiency and increases costs. If the location along the tube is known, faults can be repaired and the generator can be run with a decent efficiency. The program at Argonne is concerned with determining how the data from various nondestructive evaluation techniques correlates with the data measured through standard destructive techniques. One method of gathering nondestructive data is from an eddy current system. Based on this data, estimates for depth, orientation, and position of flaws are calculated. Later, the tube is examined destructively and the NDE estimate and actual data are compared. The hope is that with further development, a stronger correlation will be shown between the two.