PWSCC tends to occur in which components of the reactor primary circuit?

• A. Welds and bends in the reactor primary circuit.
• B. Outer surface of cladding.
• C. Control rods.
• D. Containment structure.

Answer: (A)

PWSCC happens where a high-temperature, high-purity primary-water environment meets susceptible materials that are under tensile stress. In the reactor primary circuit, the most vulnerable spots are welds and bends. Welding introduces residual tensile stresses and creates heat-affected zones with microstructural changes, and bends or complex geometries concentrate stress, all of which promote cracking under the reactor’s operating conditions. The outer surface of cladding, control rods, and the containment structure are not primary-circuit components exposed to the same combination of stress and environment, so they’re not the typical sites for PWSCC. Hence, welds and bends in the reactor primary circuit are the places PWSCC tends to occur.