Nondestructive Evaluation of Materials and Structures

The Institute is a recognized leader in nondestructive evaluation (NDE) research and development, notably in support of commercial nuclear power plants worldwide. Technical priorities during the past year included designing and fabricating enhanced data acquisition and analysis instrumentation, improving several mechanical manipulators for automated data collection, and developing specialized techniques for flaw detection and sizing. Other areas of NDE research include aerospace, military, petrochemical, and transportation infrastructure applications.

SwRI has received an R&D 100 Award for a turbine disk rim ultrasonic (UT) inspection system that does not require blade removal. The awards, given by R&D Magazine, recognize the 100 most significant technical achievements of the year. The new inspection system greatly reduces the cost of examining blade attachments for stress corrosion cracking, which can cause blade release resulting in major damage to turbines, high repair costs, downtime, and the need to purchase replacement power. A vital part of this system is a set of CAD/CAM programs that enables efficient analysis, design, and manufacture of the optimum acoustic lens and inspection procedure for each disk. The system is being used in inspections in the U.S. and Japan.

Steam generator turbine disks such as this one are increasingly subject to stress corrosion cracking (SCC) as power plants age. SwRI scientists recently received an R&D 100 award for an ultrasonic focused probe inspection system that accurately and economically locates existing and potential areas of SCC.

The Institute demonstrated that its automated examination equipment, procedures, and personnel can reliably detect and accurately size flaws in thick-section steel plate as part of the U.S. nuclear power industry's Performance Demonstration Initiative (PDI). Evaluated by the Electric Power Research Institute and conducted in accordance with the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, the PDI required SwRI to locate and characterize hidden, embedded defects of varying sizes in the welded sections of seven thick-section steel specimens (the largest weighing more than 10 tons). Ultrasonic examinations were performed using a remotely operated scanner and the SwRI-developed Enhanced Data Acquisition System (EDAS^TM II). The Institute is the first organization participating in the PDI to qualify detection and sizing techniques for both boiling and pressurized water reactors, and to qualify sizing techniques applied from only one side of a specimen.

Inspection of weapon systems using conventional nondestructive techniques is highly labor intensive. Institute scientists are assisting the U.S. Air Force increase the speed at which large surfaces such as wing skins are inspected, using a prototype system known as pulsed infrared thermography.

The EDAS^TM II is a state-of-the-art UT inspection system for use in the NDE of large structures. Designed to allow rapid and effective examinations of nuclear power plant reactor vessels, EDAS^TM II includes eight programmable UT instruments, eight real-time waveform averagers, and data acquisition and analysis workstations. The system, which can reduce inservice inspection outages by about 30 percent, or two and one-half days, records full waveform data from up to eight data channels simultaneously at scan speeds of up to six inches (150 mm) per second. This system represents the newest generation of SwRI's enhanced data acquisition equipment, used to inspect 15 percent of the world's reactor pressure vessels (RPV).

To simplify and expedite flaw characterization in metal materials, Institute engineers use three- dimensional visualization techniques to analyze eddy current signals as a function of frequency.

To further reduce RPV inspection times, the Institute has developed a modified inspection module and accompanying quick-change unit for use with SwRI's Inservice Inspection-2 device that includes an eddy current examination capability. The quick-change unit was previously used only with UT instrumentation. The eddy current version was used successfully for the first time to inspect a cladded surface in an American-built pressurized water RPV.

Magnetostrictive sensor technology provides SwRI engineers with a rapid, cost-effective means of inspecting the structural integrity of steel pipes as well as developing methods to control vibration, noise, and dynamic impact response. The technique can be used to inspect several hundred feet of pipe from a single sensor location.

Institute engineers continue to develop cost-effective NDE technology to inspect steel tubes and pipes in processing plants and power generating plants for the oil and gas industries. A new technique using magnetostrictive sensors (MsS™) provides a rapid, 100 percent volumetric inspection of tubes and pipes for corrosion defects and cracks. The technique can inspect several hundred feet of pipe from a single sensor location. The sensor is noncontacting and thus does not require couplant, nor does it require removal of paint or coating from the pipe. The MsS technique has been applied to pipes up to 16 inches in outside diameter and can detect a defect with a cross-sectional area of about one percent of the total cross section of the pipe wall.

As part of a multiyear contract for Westinghouse Hanford Company, operator of the Hanford Nuclear Reactor in Richland, Washington, SwRI continues to participate on the Tank Waste Remediation team. The team is charged with determining the condition and contents of all nuclear waste storage tanks at the facility. A specification was completed for an inspection system of double shell tanks being considered for future storage of treated nuclear waste.

In the harsh environment of gas turbine engines, surface coatings protect many components. The Institute has demonstrated an eddy current testing technique to measure coating thickness, an important factor in determining preservice coating quality as well as inservice degradation. The eddy current technique employs multiple-frequency eddy current technology, portable eddy current instrumentation, and specialized fixtures and probes.

1995 Annual Report SwRI Home