Which nondestructive examination methods are routinely used to inspect welds in a nuclear plant?

• A. Ultrasonic testing (UT), radiographic testing (RT), dye penetrant testing (PT)
• B. Ultrasonic testing (UT), radiographic testing (RT), dye penetrant testing (PT), magnetic particle testing (MT), and eddy current testing (ET)
• C. Ultrasonic testing (UT) only
• D. Radiographic testing (RT) and dye penetrant testing (PT) only

Answer: (B)

Weld inspections in a nuclear plant rely on a mix of nondestructive methods because no single test can catch every possible flaw in a weld. Each technique targets different defect types and has its own strengths and limits, so using several together gives a more complete assurance of integrity.

Ultrasonic testing looks into the weld volume to find internal flaws and can measure thickness, making it good for detecting voids, inclusions, or lack of fusion inside the weld. Radiographic testing uses X-ray or gamma rays to create an image of the interior, revealing volumetric defects that might be hidden from surface inspection. Dye penetrant testing exposes surface-breaking cracks by allowing a penetrant to seep into openings and then visible development, which is especially useful for cracks that reach the surface. Magnetic particle testing magnetizes the material so surface and near-surface discontinuities attract iron particles, making cracks detectable on or just beneath the surface in ferromagnetic welds. Eddy current testing induces currents to sense near-surface flaws and variations in material, offering rapid screening of surface conditions and crack detection in conductive materials.

Putting these together covers internal and near-surface flaws, surface-breaking cracks, and a range of materials and geometries, aligning with the stringent integrity requirements in nuclear plant welding. The other options omit one or more of these methods, reducing the ability to detect all relevant defect types. This is why the comprehensive combination is the best answer.