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Taking into account the mechanism of pitting corrosion in the heat transfer tubes of steam generators discussed earlier, as well as the relevant background regarding its safety implications, the current mainstream repair methods are as follows: In-situ treatment of minor defects. For shallow pits, sandpaper grinding can be used to remove the highly active plastic-deformed areas surrounding the pits, thereby destroying the micro-crack structures that can lead to stress corrosion and significantly reducing the susceptibility of those areas to stress corrosion cracking. Treatment of unacceptable defects in heat transfer tubes: For heat transfer tubes with indentation depths exceeding the allowable limit or those already exhibiting microcracks, mechanical plugs made of Alloy 690 are used to seal both ends of the defective sections. This isolates the defective portions from the rest of the system. Additionally, stabilizers can be installed inside the tubes to prevent them from vibrating and damaging the surrounding intact tubes. This is currently the most widely used and proven solution. Local lining repair: For pipe sections where the location of the defect is suitable and where repair is still feasible, a new tube that fits well is inserted into the damaged area to restore that section’s pressure-bearing capacity and heat exchange performance, thereby avoiding the loss of heat exchange area due to complete blockage of the pipe. The new cold spray repair method utilizes a fully solid-state cold spray process to create a corrosion-resistant coating in the areas affected by pitting corrosion, without any heat-affected zone. This approach not only helps to compensate for local dimensional losses but also prevents further corrosion from occurring. This technology is currently being tested on a practical level in the nuclear power sector. Stress regulation-assisted repair: Rotary shot blasting/scattered shot blasting is applied to the stress concentration areas surrounding the indentation, thereby introducing uniform compressive stress on the inner wall of the tube and counteracting the residual tensile stress caused by the indentation, thus enhancing the tube section’s resistance to stress corrosion.