How to Improve Steam Generator Tube Inspection Processes and Prevent Critical Failures

Steam generator tube inspections are a critical component of routine maintenance in the power generation industry. Steam generator tubes are among the most vital safety barriers within pressurized nuclear reactors (PWRs), and underlying defects can degrade the tubing material and damage the entire steam generator, causing severe problems that can endanger crew members and the public. Using cutting-edge eddy current testing (ECT) instruments and techniques fosters more comprehensive safety inspections and increases early detection rates of flaws that can potentially develop into critical failures.

There are also bobbin probes designed exclusively for steam generator tube inspection, in addition to probes that have bobbin/array combined capabilities. With high-grade ECT instrumentation and bobbin/array probes, analysts can detect aberrations such as cracking and accurately provide suitable recommendations for repairing or replacing damaged parts long before a situation becomes hazardous.

Stress Points

ECT is one of the best methods available for tube inspections because it reports stress indicators instantly on inconel, monel, or stainless steel materials. Steam generators transfer thermal energy, but the thermal transference and heavy stress can weigh heavily on the tubing material. Tube wear can compromise the efficiency of the generator, and it can manifest in the form of:

• Vibrations against nearby tubes
• Friction against various support units
• Intrusions from foreign objects 

Foreign objects can also result in rapid water flow that places more stress on the material, causing degradations, ruptures, and leaks. Many NDT methods can detect these flaws, but it takes a special kind of instrument to detect abnormalities during the early stages. 

Dynamic Instrumentation

Ideally, aberrations can be detected and averted early using specific ECT probes, but it takes high-quality probes with application specific features produced by an established NDT company to achieve the detailed data needed. Many of these aberrations are subtle, and NDT instruments cannot always detect minute malformations. That’s why it’s important to purchase quality instruments from a trustworthy NDT provider. Analysts need an instrument that can detect early-stage cracking and, ideally, is also conducive to most tube materials.

However, only high-quality, purpose-built ECT instruments can offer the inspection accuracy necessary to pinpoint even the most minor flaws. Instruments equipped with multiplex and simultaneous injection features are particularly preferable. Multiplex frequency capabilities can provide highly detailed and comprehensive scans of crack formations and other flaws, while simultaneous injection capacity promotes faster testing speeds and impressively reliable data.

Advanced Software

According to our research, automated analysis software is becoming a key component of nuclear power plant NDT processes. The software can analyze and process large amounts of data, hastening the inspection process by saving analysts time that would otherwise be spent processing large amounts of complicated data. The software can also trim operational costs in the following ways:

• Higher processing power
• Multiple analysis algorithms
• Mitigates the potential for human error

This software can also be used in conjunction with bobbin or array probing, as well as probes with mixed bobbin/array features. With automated analysis software, ECT probes offer deeper, more detailed flaw analysis on a level that most other NDT options cannot compete with.

Precise Probes

Inefficient inspection strategies may keep personnel in hazardous environments longer than necessary. In addition to advanced software and instrumentation, utilizing quality probes with advanced capabilities can keep inspection times to a minimum without sacrificing data quality or inspection comprehensiveness.

A single ECT instrument can achieve a one-pass inspection measure while producing highly reliable results in the process. This is made possible by using an array/bobbin probe that’s faster than other options such as motorized rotating pancake coils. The ideal probe for inspecting steam generator tubes will contain array coils that can probe circumferential cracking along with other hard-to-find anomalies. 

Achieving the Best Steam Generator Tube Inspection Results

When it comes to steam generator tube inspections, combining features of bobbin and array probing will allow analysts to conduct more thorough inspections. For the highest quality data possible, analysts should be equipped with advanced ECT instrumentation featuring multiplexed frequencies, advanced automated analysis software, and simultaneous injection features—all of which can help streamline the inspection process and allow analysts to find more flaws in less time.

The right equipment allows companies to spot underlying inconsistencies that could cause deviations within PWRs and spark accidents. When applied appropriately, ECT instruments are among the best tools that companies can rely on to issue the necessary preventative maintenance strategies and continue to protect the wellbeing of employees and public consumers alike.

Zetec is an experienced NDT company specializing in innovative nondestructive testing solutions. Contact us to find out more about how to improve your steam generator tube inspection processes using cutting-edge ECT instrumentation and software.