Magnetic flux leakage for measurement of crevice gap clearance and tube support plate inspection. Final report

Nondestructive testing of Inconel tubing in the tube/support plate (crevice gap) region is a critical aspect of the overall testing program for nuclear power plant steam generators. Estimates of crevice gap clearance are required together with indications of magnetic buildup at the tube/support plate interface that could lead to tube denting and support plate fractures. This report describes the results of a feasibility study whose major objectives were to: (1) determine if a simple type of variable reluctance probe would be sensitive to changes in crevice gap clearance, magnetite buildup, and support plate defects; (2) develop a finite element model for the prediction of probe output signals under a variety of crevice gap conditions; and (3) carry out design studies for the development of a prototype test unit