Study on the Step by Step Process and Performance of Laser Welding for the Spent Fuel Pool Floor

In order to realize the steel liner underwater repairing of the spent fuel pool of the third generation nuclear power plant, the laser welding process tests were carried out step by step in three environments: air, shallow water, and simulating-repairing of the spent fuel pool floor(high-pressure condition). Through the process optimization, the high-quality forming of the underwater laser welding of duplex stainless steel was realized, and the underwater local dry laser welding process suitable for the spent fuel pool floor of nuclear power plant was developed. The results of nondestructive testing (including visual testing, liquid penetrant testing, ultrasonic testing, and radiographic testing) of welding test pieces under three environments were qualified, and the test results of properties (including tensile, impact, bending, intergranular corrosion, and ferrite content) meet the standard requirements. The underwater weld performance is similar to that in the air environment, and the weld quality meets the requirements of the spent fuel pool construction standard, laying a technical foundation for the application of the spent fuel pool underwater repairing.