Improved eddy-current inspection for steam generator tubing

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5489833

Dodd, C V; Deeds, W E

The Oak Ridge National Laboratory is working on a number of steam generator and eddy-current problems, and one of the most promising developments is the use of reflection type probes. This probe consists of a driver coil encircling and coaxial with two pick-up coils, which are connected in opposition. The reflection probe is mounted perpendicular to the tube axis with one pick-up coil pressed against the surface like a pancake coil. Studies were performed to determine the best probe dimensions to maximize the ratio of defect signals to the undesired od property variations at different frequencies. Comparisons between reflection probes and the traditional circumferential or bobbin probes show that the former are more sensitive to defects and less sensitive to variation of properties outside the tube, such as tube supports, magnetite, and copper. The probe can be used in either multiple frequency or pulsed instruments in a manner similar to the bobbin probes. Since the undesired property variations have a smaller effect on the signal, they are easier to eliminate using multiple frequency or pulsed techniques. This has been demonstrated by test runs on standard steam generator tubes with different types of defects and different property variations. The reflection probe has given measurements of actual IGSCC cracks that compare well to the metallographic results. This type of probe has very good resolution and gives fine and accurate scans of the tubing, but is more expensive, complex, and slower. 10 figs., 2 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5489833
• Report Number(s): CONF-8710111-29; ON: DE88001769
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220300* -- Nuclear Reactor Technology-- Fuel Elements
440300 -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
BOILERS
CHEMICAL REACTIONS
CORROSION
EDDY CURRENT TESTING
ELECTROMAGNETIC TESTING
INTERGRANULAR CORROSION
MATERIALS TESTING
NONDESTRUCTIVE TESTING
NUCLEAR FACILITIES
NUCLEAR POWER PLANTS
PITTING CORROSION
POWER PLANTS
RESOLUTION
STEAM GENERATORS
STRESS CORROSION
TESTING
THERMAL POWER PLANTS
TUBES
VAPOR GENERATORS